Chasing P0171 again

P0171 keeps popping up, done so far : changed air filter,gas filter.
cleaned IAC and TB , checked for vacuum leaks nothing found.
Just bought car a month ago, previous owner just did plugs, wires look new.
Sometimes a P0441 - Purge flow code will also show . What should I do next :
smoke test( Cost ? ),O2 sensor replacement,fuel pressure test. Car sumbles a slight bit at idle, but runs great any other time. Mileage seems good at 24 mpg mostly highway. Cold starts good, code usually occurs after 1-2 minutes upon cold start. Help

OBD-II Trouble Code: P0171 System Too Lean (Bank 1)

See "Possible Solutions"

Sorry : Forgot : I also changed the PVC valve.
Looks like fuel pressure is next ?
One other thing , gas gauge stays pegged most of the time, past FULL.
Could that be confusing anything and throwing the code ?

Bad 02 sensor possibly since the o2 reads the afr in the exhaust which is producing this code.

If you've done everything reccomended up to the fuel pressure, I would replace the o2 or do a fuel pressure test next.

Thanks, I Think I will run out in the morning and get a fuel pressure gauge.
Any recommendations as to brand ,limited budget, trying to slowly outfit my garage.

I'd just rent one from Autozone. Pay for it, take it back and get your money back.

do you mean there tool loaner deal ?

I own this code.

Search on my username and the code number. Also talk to falconJohn about the code.

He was unable to do anything about it, and after replacing his corroded to another planet battery cable, things are getting better. Not 100%, but I've suggested the other cable as well.