Okay, I went and talked to my mechanic again, it appears that the crank-cam correlation value is out of spec. It is stuck at 6 degrees, no matter what he did. Since the vortec V6's have a non-adjustable distributor, it has to fix the correlation in the PCM. The easy solution is to make it adjustable by swapping out the V6 hold-down with a V8 one. I guess I will pull the one off the 283 this weekend.