Missing at freeway speeds

[CG]

My trucks (71K20 350 4spd) basically been sitting since August. Moved it from front yard to back last time I drove it. I mostly just use it as a truck, hauling junk, towing more junk lol. But ever since I got it a couple years ago there is a miss at freeway speeds. Nothing terrible but it sure makes me nervous so I was never far from home, and only took back roads.

I checked everything I could think of, even asked here on the board. Well back before I moved it to the back yard my son and I were sitting there staring at the engine with the air cleaner off. He noticed one of the vac plugs on the carb looked funny. He went to pull it off and the tip pulled loose. We found another larger one the same way. So I replaced them. Never bothered to test drive the truck (stuff came up right after that).

This weekend I got a wild hair and decided to take the truck for a spin (literally, it was stuck in the grass) 4 wheel drive took care of that. I drove all over. Up to Sultan, back to Everett and back home to Monroe. Zero problems at any speed. That has never happened since Ive owned it.

So I guess what I'm saying here is check your old vacuum plugs on the carb. They can cause weird stumbling problems at higher speed if they are cracked a little.

Next I need to figure out what that horrible clunking sound is when Im putting around (sounds like a drive shaft clunking). Im the second owner and the original owner told me he had the truck back at the dealers many times trying to figure out what the noise was and its never been figured out after almost 40 years on the road. Maybe it will go away when I switch it over to automatic?

Gotta love these old rigs =)



Mark