my 87 GMC K2500, 350 engine runs good for a bit and then it starts popping, banging and farting thru the carb. I have had it at the local GM dealer ship and spent $856 so far and it still runs like Sh!!t. replaced the dis cap set the timing, checked what few sensors there are on it, checked vacuum hoses and routing and now I am lost. anyone got any ideas?

 

For sure it is timing goin off. The timing gears were made of nylon from the factory and so the teeth would become very weak after so many miles. Even the distributor gear had the same problem. I would look at those.

 

For $856 at a dealer I would have expected them to think about the gears being worn out. One thing to check is when it starts doing it check the timing and see if its right...I bet it wont be and it will jump all over the place....that means the gears are probably worn out........Didnt the 87 have the ESC (Electronic Spark Control)?

 

checking around I found a ground wire behind the engine that was loose on the engine as well as the firewall tightened both and the popping and banging went away. I was so happy I could again plow snow from my driveway I had at it and destroyed the inner axle shaft on the left side so back into the garage for repair. Thanks everyone for the help.

 

Glad you got it fixed! Jus for assurance, I would add another grounding cable. I have done this to all my vehicles.