I have an 85 TA with automatic transmission (presumably 700R4). Today while driving at somewhat higher than highway speed I encountered a shifting issue. i pressed the gas hard but not WOT. The downshift to accelerate was fine but when the transmission tried to shift back presumably from 3 to 4 (it was in OD), it was like it could not get into the gear properly until I took my foot of the gas a bit. Shifts under easy acceleration are fine.

Fluid and filter were changed 2 years ago when I bought the car and I have driven it maybe 5000 KM (3000 miles) if that. Fluid level is fine and no fluid leaks. I recently had transmission mount replaced but did experience this shift problem once before that was done. I don't hard accelerate often so whatever the issue is may have been present for who knows how long.

I have done some looking around for what the problem might be but can't find anything that sounds exactly like what I am experiencing. The shift back to 4 from 3 is only an issue during hard acceleration. No issues on easy acceleration.

Any thoughts?