My wife has a 92 Ford F150 that seems to hunt for gears about 30 - 40 mph. It feels like its upshifting and then down shifting really harshly. Also, intermittently,the engine will rev, as if you tapped the gas pedal in neutral when you come to a stop. Recently, I flushed the trans using a T-Tech machine which taps into the cooler lines, and has a large clear cylinder with a piston inside. On one side of the piston is the fresh fluid, and on the other is the dirty used fluid. As the trans pumps the dirty side full, the piston pushes on the clean and pumps in fresh to the trans. After doing this, I dropped the pan and changed the filter and gasket. I also recently had to change the TP sensor, as the insulation on the pigtail wires has came off to where the wires could cross and send faulty signals back to the ECM. While I had the throttle body off, I took the oppurtunity to clean the throttle bores because they had heavy deposits on them, as do many vehicles w/ 95K miles or so. I work at a GM dealer, and asked the trans specialist if he had any ideas, and he told me he wasnt familiar w/ the newer Ford transmissions, because the only ones they had when he worked at a Ford garage were the C4 and C6 styles. He did mention that it could be the torque converter clutch that we were feeling. On that note, I tried pouring in a can of Trans-X, and that seemed to take some of the edge off the harshness, but didnt solve the problem.