Working on a 95 Camaro 3.4L. Just replaced head gaskets as cyl #5 had the infamous leak. Back together, and it runs great in open loop but then starts to stumble in closed loop and throws a DTC44 for left O2 sensor lean. I have a scan tool and verified the O2 sensors are reading fine in Open Loop but the Left goes to nearly 0 in closed. Vacuum lines are tight and no signs of leaks...Any help is appreciated....Also I switched the 02 sensors with the same results. Even ran the car with the 02 sensors breathing outside air and it runs superb...Map sensor appears to read properly as well.

 

check your fuel injectors for leaks. if ur running lean you r not getting enough fuel. check the fuel pressure. should be around 40 psi at start up. then drop a tad at idle.