Had problems with major hesitation and chugging. Replaced plugs, wires, fuel filter, MAF sensor, O2 sensor, intake manifold gaskets, all vacuum tubes, PCV valve, cleaned throttle body and injectors. Had a major chugging problem and pushed one of the wires on top of one of the injectors and it 'clicked' and it didn't chug that bad anymore. Still have a slight chugging problem though. Before i replaced the MAF sensor, i got error codes 34, 42, and 44. Haven't had a chance to check yet. Like i said, it says it's running lean, but i already replaced the O2 sensor! PLEASE HELP!!!!!

Did you check the wires going to the other injectors ? Also, are all the plug wires on tightly ?

Yeah, i replaced all the wires and put them on tightly and made sure all the wries to the fuel injectors were on tight. I can't seem to find any vacuum leak anywhere either. Thanks for the reply, any other suggestions?

Oh yeah, i disconnected the battery and reconnected it and ran the code checking and i have no errors it says.

If your getting all those codes, I would try the cap, rotor, and ignition controll module. Had the same problem on my friends GTA, turned out to be the ICM.

I'm not getting any codes anymore, but it still runs funny. Like when you give it a little gas, just slightly pressing on the pedal at any speed really it kinda chugs a little.