1986 300E won't shift from low gear to next until the engine is screaming at 5500 rpm or so, but will shift when I lift off the accelerator slightly. Just driving the car normal, cruising from a stop using less than half throttle, will not shift at all. The car is stuck in first gear or does it start off in second? Anyway the fluid is fresh and at the proper level with all new internal parts and seals. The car shifts normal from reverse to drive but does not "up-shift" while driving normal. Help!!! what have I overlooked Thanks.