I have a 1997 GMC Savana van with an automatic trans, 5.0 V8 with 169,000 miles. I have replaced the driver's side window motor, the window switch and replaced the pins in the wiring harness. When the engine is running (not in accessory mode) and you use the " express down" button the window stops in the fully down position and will not raise. If you wait a couple of seconds or a minute, the window raises fine. This occurs about 4 out of 7 times. I took the vehicle to my mechanic and he said all was fine. When I left the shop the problem was still present. There does not appear to be any problem with the window regulator. Any ideas?