The truck is a:

2000 GMC Jimmy
4.3L
2 door
automatic

Well as my luckmay have it my truck started acting up a week or so ago (After I prayed for snow)and after a few tests I ruled it to be a bad IMG (Intake Manifold Gasket). I did a FP test and hit had right around 60 psi with the key turned on. I didn't however do the bleed down. The truck refuses to take gas, you can however hold it at any rpm and it does fine. At idle it will sometime miss out real bad (causing a shaking of the motor). I'm sure that it could use some plugs and wires (just bought plugs and wires) but I haven't changed them out yet. It has 135,XXX miles on it but hasn't been abused no more than the next guys truck. So as said before I tore it down to replace the IMG after seeing some coolant around the lower intake and having a mechanic put it on the new Snap on scanner. At first it had a cyl. 6 misfire but then when checked again it was a p300 multi misfire. So anyways I went ahead and tore it down and I do believe that it was in need of a IMG but unsure if this could be a result of something else. When I drained the oil to change it coolant came out then oil, so it leads me to believe that this was it. But could this be the only problem? I noticed some wear on the dist. gear also but all the teeth were the same thickness, just had wear where the oil pump is driven. This just started all of the sudden, I had however noticed a sort of miss when on the Interstate and cruising (If you have ever been in a boat or plane then it feels like the drop that you experience). I put a new pump in it back in the summer and it starts just fine, till here lately and it will sometimes act like its hydrolocked for a second or two and then turn over.

Thoughts are very much appreciated as I am poor and don't have the money to pay a dealer/mechanic to fix it.

I will be setting the dist. timing today to see if the gasket fixed it. But I have a gut feeling it won't

 

Have you checked the fuel pressure regulator to see if it is leaking? On your intake manifold, is it all black from carbon build up, but where cyl 5 & 6 are clean?

Pull the plugs on each cyl and see if they are saturated with gas, if they are misfiring then your injectors might be screwed. A new spider costs around 185 on rock auto parts.


I had a bad miss when I bought my truck, and it was the spider that went back, and the fuel pressure regulator was going as well. When we did it, we replaced both the upper and lower gaskets, they were on their way out as well.

 

Hey i have a 2000 chevy blazer 2 door auto, and i have a miss as well i have a misfire on cylinder 3 and ive replaced the entire ignition system and still its missing, the only thing i didnt replace was the spider as said above, just curious what comments are out there i too am broke and cant afford a shop or dealer parts. if its any help before the full blown miss on 3 when i would go above 3000 rpm on the highay from pushing it past 80mph it would flash the CEL and i would hav it read and it said misfire on 4 and then it would go away. please if anyone knows anything that can hel me trouble shoot this.