I have 74k miles and this just recently started happening. This jerking/hard shifting ALWAYS happens when I'm going up mountain hills and it seems like it happens when I'm in 4th gear and need to drop back into 3rd to get more acceleration. It makes a thumping sound and jerks the car, and mostly never gets into the needed gear. I already took it to the Lakewood Ford, off of 6th and Sims, but was told nothing was wrong and they even did a $160 DIAGNOSTIC TEST... Any help, suggestions would be MUCH appreciated!!