2002 Blazer 4.3 Yes I know about the TSB and all the problems with this unit. I had to take it to another mechanic (who I trust) because my son's work doesn't have a scanner to do a crank relearn. I took it in Thurs. for a crank relearn, and the problems began. First the SES light just came on. misfire code on Cyl 4 and 1. Cleared them and drove back to work. SES light starts blinking. Cr@p! Back to the mechanic. It it misfiring a bunch on Cyl 4, especially above 1700 RPM. replaced brand new Dist. cap with another one. no help. Left it with him to see what he could do. He informed me Sat. morning that he has no idea what's wrong, but the voice mail didn't tell me what he did, so I can't eliminate anything until I talk to him monday. I assume he tried wires and plug (both of which are brand new, and yes the plugs are the correct AC Delco plugs) You can here a lean rattle when it starts misfiring, so I don't want to drive it, but my truck has the entire front axle out of it. It is probably going to stay that way for a while, since I can't afford to fix both vehicles right now. I think that I may have to go with the upgraded spider to fix this, so I am looking for a decent price online right now. It also has a crack in the lower manifold that needs fixing, and I found a brand new entire upper and lower manifold with CSFI and throttle body for $329 plus $30 shipping, I might go that way too. I really don't know yet, I will know Monday what I am looking at.