Hi, I need help: My 1997 Taurus at the road showed 3000 RPM at 50 mph. No overdrive. Changed to second shift and car goes smoother. Back to D enbgine gasps, no acceleration, RPM goes up and down and converter disingages. Had to change to 2 speed to complete travel. Any attempt to change to D and accelerate, engine immediately hesitates and shuts off. Any ideas? Many thanks.