My 97/350 E40D does that occasionally also. Where is the idle validation and the throttle position switch located on the 7.3 as I`m almost sure your suggestion to clean with contact cleaner is what mine needs. TIA.mine does this occasionally. it is the torque converter locking up. it won't unlock during shifts making for a very hard shift, and it locks way to early making it feel like a manual. my superchips tuner says it is a throttle switch. that means it is either the idle validation switch or the throttle position switch. worst case is you have to replace the pedal assembly which gives you both switches for about $200 (Ford Parts and Ford Diesel Parts at Powerstroke Shop). easy solution is to clean the terminals on both switches with some good contact cleaner / oxidation remover.