Bank 1 and 2 lean

What do you have for codes ?
Save time and money and have it smoke tested

E85 compatibility is designated for vehicles that are certified to run on up to 85% ethanol and 15% gasoline. All other gasoline engines are designed to run on fuel that contains no more than 10% ethanol.

If using low E85 in a none E 85 certified engine will cause lean condition codes

I belive the code is P0171 and P0174.

I also only run Mobil or Marathon gas through it and it is all 87 octane accept for the occasional Premium/93.

Will smoke testin act the same as checking the vacuum lines with break cleaner?

Smoke test more accurate than using other methods to check for vacuum leaks
also try and have the injector cleaned

But would a leaking vac. line or intake mannifold cause the light to continue to go on and off?

I have been waiting for this to happen again.

I have replaced the MAF, TB gasket, Fuel Filter, Plugs, Wires and all that good stuff.

It has been warm latley, (40-50F) and my truck doesnt throw the P0171 and P0174. But again the other day the temeperature dropped and now the truck is throwing both of those codes again. I have been running at least 83 octane fuel and have looked for vacuum leaks but am not sure of all the vacuum hoses to check. My next step is the replace the EGR valve and the cooland temperature sensor. Would these be a wise decision or what would be casuing the problem?

Should have the injectors cleaned and smoke test the intake manifold for leaks

But if it were a manifold leak would the SES light continue to go on and off over the course of a few days, especially when the weather gets warmer? Seems as though the gasket would either be cracked or not and not cause the light to continue to go on and off.
Also if it were the injectors would I experience a lack of performance in acceleration or power? I currentley am not experienceing any engine difficulty accept for the SES light.