3rd tank of E85 in a 2007 camry, started getting check engine light and P0171 code, do you think the error is being caused by gas or other problem?

If your car is not rated for E85 you are lucky it runs at all. Use E10 or 100% gas next fill up.

I checked and Toyota never made a Flex Fuel Camry. Stop using E85!!!

Did you check for a vacuum leak?

thanks guy, yea my gut says once i start using 100% gas it will go away

how do you check for a vacuum leak?

With engine running at idle spray brake cleaner around intake area intake tube and vacuum lines,If you have a leak the idle will change,It will increase,go down, and if it's a really bad leak it will stall the engine.

I guess my vacuum lines are kinda hidden to me, is there a diagram of a 2007 camry that can show me where all the vacuum lines are?

Doesn't matter, your trying to find a leak, when you find the affected area then you will start looking for the cause.

For vacuum leak use a smoke machine to find the leak and being someone who own a 07 E85 is real good at cleaning there for will make all the dirt and rust in tank loosen up that 07 camry does not have a fuel filter from factor so all the dirt and rust will find their way into the fuel pump and injector causing premature failure