'96(pre-electronic) C36 tranny shifting late @ 55K

[stroked 1/2 dzn]

My tranny recently started shifting late(holding the gearchange too long) through all gears intermintantly at part throttle accel & even 60-80% throttle angle. It will do this from cold fire up in morning to the end of a 30 min drive. But lets say after sitting for 30 min & driven on a short trip it wont do it?

I can get it to go away by shutting off the car & turning it back on. This leads me to believe with most certainty that it is a sensor or something electrical that affects hydro line pressure. It feels like the torque converter is not 'locked' either when it shifts late(like a high stall race converter)

It basicly holds gears late even after warm up sometimes(I know its normal to do that when cold up until 30mph).

This leads me to think that maybe it is computer related & it 'clears' itself after shutdown. Maybe the tranny thinks the engine is still cold so it stays in 'warm-up mode'

My fluid was changed recently(past 3 mos) It was really dark but did not contain any metal shavings or band material like some trannies do after 55K. (Tech let me look inside the pan) I dont 'beat on' my car & I drive it pretty conservatively. I told him about the symptoms and he felt no reason to believe anything was wrong inside due to the otherwise 'clean' nature of the pan. I have heard of peoples front pumps going out on these pre '97 trannies & causing pressure fluctuations & stuff(no shavings though!)? It started doing this about 2-3 weeks before I had new fluid put in.

I have had pumps fail on GM TH-200R4's & 700R4's in my old hot-rods & that is the symptom that shows its head before it fails???

Car has 62K miles

I can be Emailed also @ kiley@houston.rr.com

Thanks!