badAzz383LT1

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. Why would I be getting the VATS code though?

I know this probably makes a big difference also but I have just replaced my wiring harness with a junkyard harness since I couldn't find a new one for a 93. I have to get this car shipped from Germany back to the states in a few weeks so im very pressed for time and need help quick.