This issue has been discussed and I have worked on this problem once on one of my Duraforce lawn-Boys. I can't say that I have an iron clad grasp of the perfect fix either. The throttle assembly is not responding quickly or consistently to the throttle position (cable position) nor is it responding quickly to the governor's need to speed it up or slow it down. The throttle is controlled by a small coil spring. Any resistance from the throttle shaft or governor assembly will cause the symptoms you described and I experienced on mine. I tried loosening the screws that hold the carb on. (In case the carb mounting surface was in a bind or warped) No effect. I ended up clicking the governor up a notch and it helped but wasn't the positive fix I was looking for. It still responds too slow. Sometimes the primer hose can rub the throttle and that would for sure cause the problem so check that. The throttle shaft itself did not appear to be binding in any way and the governor wasn't rubbing anything. I'd like to hear a rock solid fix for this. Hopefully someone will chime in with a fix.

Thanks for the advice, I will take a look at the governor to make sure it moves smoothly and nothing is blocking it.

Yea.It sounds to me too like the vane is sticking.Grease, dirt or grass gets on the spring and can keep the gov. from working right. Maybe try compressed air on the spring to clean all the crud off of it or just take the carb. off and clean it.At my local electric and magneto shop they have a tachometer made by Tecumseh that works by vibration for about 10.00. This will help if you plan on adjusting the governor.2900 rpm give or take 300 is the spec. Good luck.

Yes mine has done this same thing with high reving for second beforeit goes down to normal speed then eventually one day i couldnt get it going at all last year.I have just got it back from shop for those starting issues,and i tested it when i got home it was fine and ran full power.Second day i thoguht test it again and test throttle and once i put it towards choke it would cut out engine.Today it wouldnt start at all.
Could it be same thing?.

Its a commercial orange tank one

Yeah, i just got off phone with mower repair and it seems to be the vaine like stated above in other post.Shop also said his throttle wouldnt let him change speeds last night on his lawnboy so this must be a common issue for mowers now days.

Yup. I have two of my three Duraforces out of commission for the same silly issues. It all started last year on 3 relatively newer mowers. I took my 10323 coil, and used it last season when my 10550s coiled crapped out. Then the 10323 became a doner again when the 10550s carb would not work. The loosening of the carb screws worked temporarily, but everytime I used it, it was problematic. I carried around a screwdriver or can of lubricant while mowing to monkey around with it. Now my commercial has the issue, and the 10323 is left with no parts to spare. Geesh. Pain in the butt.

Regarding the high rev that Tex is experiencing,this is normal due to the jet and holes.The issue i have posted earlier is likely the spring wore out or disconected from the vaine

meaning the not starting issue

ok its fixed,it was what i originally thought it had to go in for,the ignition spark plug thingie coil whatever.

My 10550 started experiencing the air vane 'sticking' symptom but I haven't tried to fix it yet. Since I know the carb area has a good coating of dust/crud, I'll first clean/wash it, then take a close look. Anyone having this symptom of very high RPM on start and/or no response to the manual throttle lever should start at the throttle lever and check every component right through the air vane AND into the air shroud just to see if everything is clean and free.
Throttle system operation: The governor spring holds the air vane and throttle plate in the carburetor in the wide open position - the throttle plate is set into the stem of the air vane. When the engine is running, the forced air from the flywheel blows the air vane toward the closed throttle position. The governor spring resists closing the throttle according to the position of the hand throttle control. The throttle cable moves a slider atop the air filter box left and right. The governor spring end is attached to the slider. The slider moves as the throttle moves to the 'Fast' position, increasing governor spring tension, resulting in higher RPM. The RPM range from idle to top speed is adjustable to a degree with the adjusting collar at the base of the flywheel - clockwise increases spring tension resulting in higher RPM.
As you can see, there are numerous opportunities in this system for sticking or binding. I think most cases are the result of contamination in the governor spring area which possibly could benefit from being blasted clean with CRC Electronic Parts Cleaner (plastic-safe). If there is varnish build-up in the carb throat, it could restrict throttle plate movement. A quick check on the governor spring is (with the engine off), remove the air filter and observe the throttle plate, which must be in the wide open position. The air vane must move easily and freely and instantly snap back to wide open when released. If this is the case with your mower, you can eliminate the carb, air vane and governor spring from consideration (except for possible adjustment). You then need to look at the sliding controller, governor spring connection and cable control for the problem.

I posted this same problem a couple weeks ago. I just had the carb rebuilt, so everything is clean and working. But still stalls every five minutes. If I hold the vane open by hand it keeps running until I release it. I wait a minute, restart and cut 5 more minutes. I am having the repair shop contact lawnboy. I will post if I find out anything worthwhile.

Stu: Put four clicks on the adjusting collar (clockwise, 'righty-tighty') to see if it improves. Continue until it gets right. Sounds like the shop forgot to set governor speed.

Saxman: Worked like a charm. But I had to go counter-clockwise. I can't believe that is all it took. I thank you. And my wife thanks you! I was not fun to be around.

Are you going counterclockwise (looking straight down)

The vane was sticking on my mower as well. I noticed tha when I completly loosened the mounting screws, that the vane worked freely. After several attempts to fix the problem, I ended up removing the vane shaft from the carb. and drilling the shaft bore out a very tiny bit larger. I used a drill bit that just wouldn't go through (I could have forced it) and it removed only a very small sliver of plastic. If I remember right, I had two use two different size drill bits due to a step down in the shaft bore. The vane vow works perfect and the mower runs great! Oh, except that the coil is now failing.