Just a quick thought but have you checked the vacuum advance canister? This sure sounds like it is timing related.

Edit...if you suck on it, you should see/feel it moving. Usually it doesn't take a lot of vacuum before you start to notice movement.

Last edited by Jon G; 08/02/2024 2:18 PM.

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end