I just rebuilt a 350 for my 90 chevy pickup. The engine was bored .030 and at the suggestion of my machine shop I put a different cam and lifters in it to increase gas mileage. Timming has changed from TBC to 5 before TDC. I ran it through the break in for the cam (2000 rmp for 20 min). But then I started to get codes. It has coded 32, 33, 45 and the last one was 15. I have changed the egr, tried a different MAP (but got the same result so I went back to the orginal) and I changed the O2 sensor. The O2 was the last thing I changed and it was very black from carbon. I can see gas pouring in from the injectors (very wet spray pattern).

I was thinking the cam may be causing the problem but I'm not sure what to do to fix it. When I checked the vac at the manifold it was just about 17 with a small rapid fluctuation.

Any suggestions??
Dan