Ok new to the forum and I know this has been mentioned a number of times and I did look through the forums and found nothing. The issue is a po300 code that started last week driving to work. Long story short fuel pressure is good and holds, compression is good and holds. So far parts that have been replaced consist of spider injector, fpr, wires, plugs, cap and rotor, and distributor but yet problem still exists. What baffles me is when I pull wires from the distributor (5,1,3) no change in idle as well as fuel dumping out the exaust. When in the vehicle you can definitely feel the missfires. Can somebody please point me in the right direction.

 

Forgot to mention it's a 2000 jimmy 4x4

 

Have you tried AC Delco brand cap and rotor? I have found that aftermarkets aren't designed correctly and short. Chased P0300 for a while until someone told me about the aftermarket problem caps.

 

Yes ACDelco everything it's the only part I'll put in it. I even tried swapping the coil and nothing.

 

I would inspect\clean the MAF and make sure the TBI cover gasket is still good and make sure the air induction system is secure with no leaks..

 

Double check the seal where the spider comes through the upper plenum. these are known to leak vacuum if they do not seat correctly. i had to use a lubricant on my new seal when I replaced mine to get it to go down all the way.