99 Rodeo CEL error code P0171

I have a 99 Rodeo V6 4WD LSE with about 65K miles. The "check engine" light just came on. I checked it out with the reader and an error code of P0171 came on... which means that "System Too Lean - Bank No. 1". Not sure what to do next.

Can it be the O2 sensors? This model requires 4. Can they be fixed or refurbished?

Can it be the mass air sensor? don't even know how to begin testing for that issue.

Too much air or not enough fuel flow??

I've replace the plugs (OEM), K&N air filter, PCV valve, and was looking to replace the fuel filter. How do I release the gas pressure so i can replace it?


Please help. Thanks in advanced.

I forgot to mention that I had trouble with rough iddle before. Cold start up is fine. Hot start ups are tough. Sometimes it would start and stall out.

My guess is it is the intake gasket.

check the link at the bottom of my post.

I will agree with amigo-2k on this one
INTAKE GASKETS

Yep. Replace the intake gasket and it's fine now. To test it out, you spray brake cleaner near the four area where the intake gasket would be with the engine on. If the engine reves up, you've found your problem.