have a 2000, GMC Jimmy, which all of a sudden, just went to total crap, with misfires. It would start right up fine, but as soon as I put it in Drive - total crap. Oddly, it would drive in reverse, just fine, for the most part, but after 7rl passes, got crappy as I slowed down. I thought it was the coil, so went to buy a new one, but parts guy offered to check it with his own snap-on scanner. It showed no codes, so he drove it around 7rl blocks. It was crap again, but as he kept on the throttle, it straightened out off and on for a bit, but went back to crap. Now it threw codes for cam, and crank sensors. I made a stupid mistake, when trying to get the sensor out, leaving it loose, while blipping the starter, to get the engine, to turn over incrimentally, to get slot on the reluctor plate into place, so I could remove the sensor, but the sensor jumped, and got pinched by the reluctor plate. Replaced sensor, but now no hint of any firing. Put old sensor back in, to see if the new one was bad, but got the same result, although with extensive cranking, it did fire just a bit, enough to keep the engine coughing over, like it was firing on only one cylinder. I was going to try the new sensor again, but haven't yet, figuring it is a waste of time. What I'm thinking is that the reluctor got shifted just enough to throw timing completely off, as it is just pressed on to the distributor. Thinking of replacing the distributor. Any thoughts? Another mechanic suggested that it might be a failed distributor cap (Napa, 1 year old). He advised to only by GM electronic parts thru the dealer. Ugh....

 

I would start with the easy things first, being the cap and rotor. Had pretty much the same thing happen to me a few years back, turned out to be the cap and rotor. Easy, cheap fix. Hopefully the same for you.