Car: 91 940GL B230F and AW71L auto transmission. 250K kilometres.

I've been having a lot of trouble with the lock up function on the torque converter. For the first drive of the day in the morning it works well - locking up at about 88kmh in overdrive and staying locked up until I go back under 88kmh.

If I have to slow down again for an extended period (say over 4 kilometres) or, if the car is switched off for about 30 minutes, the torque converter starts to act up. As the car accelarates the torque converter locks up. As I ease off the throttle to let it cruise at, say 100kmh, the torque converter unlocks again.

Also, sometimes while maintaining a steady 100kmh the TC will be locking and unlocking or almost locking then letting go again. I have just had the transmission completely flushed out with the pan removed and the filter cleaned and new gasket on the pan. The new fluid seems to have exacerbated the problem. The fellow who did the job (recommended by my Volvo mechanic) suggested the problem could be caused by wear in the clutches.

To me, this seems to be a pressure related issue. As the car accelerates with the throttle almost wide open there would be a lot of pressure then as I ease off the pressure drops. Does this sound right? Is wear in the tailshaft bush the sole cause of this problem?

I'd really like to get this fixed as it's driving me mad and, surely, it can't be any good for the transmission or engine.

Please help!

Regards
Brad