HELLO. I have a 62 Econoline Pickup with 72' C4 transmission behind a 200 i6 engine. A normal driving speed (shifts up ok - 1st, 2nd, 3rd) when you let off the gas, it down shifts into 2nd gear (shouldn't it coast? ). When you accelerate it shifts back into 3rd. As you decelerate towards a stop it shifts from 2nd to 1st as it should. Supposedly the transmission was rebuilt within the past several years and not many miles since then. I have now was to substantiate this. Does anyone have a guess as to what's causing this? Or am I looking at a worm out tyranny (time for a rebuild?)?

 

I am happy this was resolved.

 

Possible govenor sticking?

 

It was a problem with ported vs non ported vacuum.