It may be good to clarify that the engine is physically cranking over- but not starting? Losing power and then going again could be as simple as a plugged vent in the fuel cap. How low was the oil? The backfire could be as simple as a failed spark plug, sheared flywheel key, coil etc.

Just tried it. It started up alot of blue smoke came out and it sputtered a bit but then I panicked as it sputtered so turned it off. Tried to start again and it wouldn't. BUT it did start. had added more oil the other day but it appeared at a good level when I went to start it. If it did start what other reasons could there be. It costs so much to bring it in to someone and its the end of the season here in CT so perhaps I'll just wait till spring. Did put some stabil in as well but have not be able to really run it through. Should I just change the oil out now or do you think its something else? Had a new coil put in 2 years ago.

How low was the oil when you added some.

it was just at the bottom of the dipstick where it "V"s. But it had been running. Kept checking it and it seemed to have remained there so added some. Its at the full line now perhaps a spec above?

to update. Its perfect (the oil)right on the mark.

Your first description of running for a while then losing power makes me think of two possibilities.
1. Plugged gas cap as previously mentioned.
2. Overheating from either running without enough oil or insufficient airflow from a blocked cooling shroud.

Remove the spark plug and let us know how much carbon is on the plug. Try a new plug anyways and report back. Any smell of fuel in the oil?

Well I started it it started right up with no blue smoke but sputtered a little with a little black smoke coming out it kept running but figured I better shut it off. Never did spark plug work I know its easy but not for me.

Rather than continuing to start the mower and shut it right off again you should take it to a good mechanic who will check out the numerous possibilities that have been suggested to you.

I have a feeling its a clogged air filter. Will try that have yet to pick one up

Sputtering could be caused by bad fuel

I'd probably be inclined to change the fuel filter (with the GENUINE Kohler replacement) more than the air filter.

I'd also smell the oil for the presence of gasoline in the crank case.
A bad carb needle & seat could cause somewhat similar problems to what you describe.
The "blue smoke" bothers me, and can indicate the oil has been thinned out with gasoline fom the carb leaking through.
Engine then gets ran for awhile and vaporizes the gas, resulting in a low oil level.

I have a JD LT 160 with a Kohler engine. After a standard replacement of oil, fuel filter and air filters last year it began quitting after applying the blades. As it was the end of the season, and being a procrastinator, I let it lie until this spring. Same power loss after applying the blades. Did the standard fuel change, fuel cap check, carb cleaning with no change. After reading this blog I found that the fuel filter was the type described in above messages that was made in Isreal. This fuel filter is from the John Deere kit purchased at a JD dealer. So I ordered the Kohler recommended part, made in India, and replaced the Israeli filter. Lo and behold, the tractor works as advertised. I will update to see if it lasts the summer.