My 85 2wd pickup with a 32/36 was running fine yesterday. Then when I was driving home I put it in neutral to coast down a hill, it ran for a bit and then shut off. I stopped and started it again and it was really chugging almost a gallop. I managed to limp it home but it never smoothed out. I tried to start it this morning and it was doing the same thing. It sounds kind of like blllap blllap bllap and when I give it gas it doesn't go away just speeds up.

 

Id Check the spark and dizzy, I maybe way off though

 

I took it to a shop and it turned out the #4 cylinder intake valve was stuck open about 3/8 in. The mechanic tried blowing compressed air into the cylinder but it didn't break loose. So until I have the time to pull the head it's out of commission.