So I took the plunge this weekend and pulled the intake manifold. I installed a new aluminum plate on the bottom (home made) and put it back together. The truck runs great when it warms up. (I wont give it a try this morning! the wind chill is -35 C) So I think I am on the right track and my next move will be the install of an O2 sensor. Then we will have it all pretty much back to factory fresh.
I cant believe the change in power after this fix. Idle speed is constant and it runs like a champ! Very pleased with the truck.
Mike

 

This is getting a bit discouraging. After the plenum fix the truck ran great. when I started it the next time it ran like S(*^! to say the least. I read the codes and they say that I need a PCM as there is an internal failure. I also need an oxygen sensor. I have these parts in hand now and have not had the opportunity to install.
Any wisdom out there? Anything to watch for or be aware of while making these changes.

Thanks for any help. Mike T

 

So I worked on the truck for several weekends and finally threw my hands in the air and took it to a mechanic with experience in computerized vehicles. When he had problems similar to those I had encountered I didn't feel so bad... Just a bit poorer!. The final cause of most of the issues was the distributor and the bushing it rides in.
New bushing and distributor and the truck runs much better. Starts right up... no backfire... good power and gas mileage.
SO check your distributor for free play. it just might save you a lot of problems.
Mike T

 

Good to know, and glad to hear you got your truck running right.

 

A great blow by blow writeup, Mike! Hope the distributor thing did the trick. Sometimes getting a fresh set of eyes on the problem helps a lot. My personal trail of tears was a late 70's Chevy pickup which after a new cam, distributor, carb, & tuneup ended up having a kinked fuel line at the dual gas tank switch! Found after I'd given up and had a shop do a diagnostic on it.