After reading several of the other posts with similar problems, I again cleaned out all the burners and orifices. I also replaced the hose to the fan/ pressure switch just in case there was a small hole. I just put it all back together and still get the same problem. The gas trips off shortly after it lights because the fan does not switch from low speed to high speed quickly enough. Any suggestions for the next step. I was thinking it may be the controller (expensive item) or possibly the Honeywell gas valve.

Have you called Pentair?

Check the stack flue sensor.....

I don't see any stack flue sensor in the manual. I don't think this model has one.

I guess I was thinking of a Master temp...Sorry...Try the link below

Here is a link that might be useful: Pentair

Thanks, I will check that link. Last weekend, I got the heater running by lowering the fuel gas pressure at the manifold by turning the adjustment counterclockwise inside the valve. I went in 1/4 increments until the heater started. I then ordered a 0-15" wc gauge so that I can make sure the pressure at the manifold is at 2.0 " wc. Once it arrives, I will post again to let you know if this fixes the problem. Hopefully, it will consistently fire up properly if the pressure is right.

When you get Pentair on the phone and tell them your model number, there will probably be a pause, and a sigh.,from the tech. Don't let that bother you.
Seriously, that can be a hard heater to trouble shoot. Get help.