I had 4L85e swap done with a 3k stall GM converter. I haven't driven the car that much but the converter stays locked and the car shifts at low rpm. When I come to a stop the rpm's drop to 400 and feels like its going to stall. Then the rpm's go up after a sec. Saturday coming home from work after having my knock sensors done, half way home the converter unlocked and was acting like it should, or like my old trans did with the 3500 stall. Then later that nite, I drove the car and it was locked again.
I don't get it. Can this be fixed with a tune? Or does it need to break in?

 

Do some research on line to lube, that was one of the problems I had with my 80E. Sonnax makes a pressure regulator valve that can be installed with the trans in the car. (# 34200-14K)

My trans had other issues that had to be fixed but installing the Sonnax valve fixed the converter clutch dragging.

 

Yep sounds like you need a line to line valve. I have the same issue with my 3000 triple disc dragging at idle and this is supposed to be the fix for that. I havnt put it in yet but I'll let you know when I do.

 

We thought this was the issue with my triple but no evidence was found by the trans guy when he put the line to lube in or by the converter guy.
The new stall (6F) is going in this afternoon.