I just finished rebuilding my heads on my 93 Z28 and when I started it up it was idling fairly good. Few minutes later it started to surge really bad and you can feel the car shudder every 5 seconds or so. I tested the codes and got code 44, the left O2 sensor running lean, and 46, which says it is the VATS. I read about how if the injectors get clogged it could cause this but does it sound more like a bad O2 sensor? I dont remember if that would make my engine surge as much as it is now. Also when it's reved up around 2-3K it sounds like a tiny missfire. The plugs were old but they looked ok why I used em again.

 

Your english is really good if you're from Germany . If I remember right the O2 sensors were not that expensive, buy a new one and see if that fixes it. If not then you know you should start looking else where.

 

Heh yeah good english sometimes... Im stationed out here in Germany. With the Army. But on the codes 44 is the O2 lean and that went away this morning. It had been sitting for 17 months and the gas was bad I guess. 46 went away also but now my left head is leaking from the rear right below the crossover bolt. Guess the head gaskets I put in crapped out already. Gonna try some bars leak and see if that stops the leak