Since I bought my '86, it has never run right. I had problems with idle, idle mixture, lack of power, stalling, stumbling, harsh shifting, you name it. Nothing I ever did fixed it............until now.
Because of my never ending mission to stop all the oil leaks in the engine, I replaced the intake gaskets. In order to do that, you must remove all the vacuum lines, and mine has a mess of them. This turned out to be a blessing, as I found two problems.
First, the main vacuum source to the thermal vacuum switch had the barb broken off. Someone had tried to secure it to the vacuum switch with a tie wrap. Autozone had the needed replacement for about $15.
Second, I decided to check the vacuum lines against the schematic. Guess what, some previous "mechanic" had changed the routing. Likely, because he forgot how they were supposed to go.
So, after straightening all that out, I now have a smooth running 305. It's not a rocket but it sure is more peppy than it was.
If you are having problems with the way your truck runs, I recommend tracing out the entire vacuum circuit. Fixing it may solve a lot of problems for you.
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