I am helping a guy replace a 2.8 V6 TBI in an '86 S-10 Blazer. Everything is back in, the motor is getting fuel and spark on all cylinders. We can get it to run, but it runs real bad and when the timing gets a few degrees advanced past 0 it backfires with lots o fire. The computer is disconnected from the distributor as per the book. Nothing seems to be disconnected and we have tested every single sensor in that thing. When I asked if the crank or cam position sensor was hooked up he said he didn't think it had one. The book mentions it but doesn't say what years had them. Any ideas? I'm kinda leaning towards rockers being misadjusted but I set them up and have done many in the past (I know what I am doing, but maybe I screwed it up?).