My 2001 F-350 has a couple of strange quirkes. The 1st is sometimes when I step on the throttle, there is no responce. The 2nd is sometimes when sitting in slow traffic (between 20 and 40 mph) and I'm only giving it a little throttle, my automatic transmission seems to up shift and down shift back and forth between 2nd and 3rd gear. I spoke with a friend of mine and he said the 1st problem is caused from a faulty TPS "throttle positioning sennsor", and he said the 2nd problem could be cured by replacing the transmission filter, but may also require replacing a vacum silinoid on the side of the transmission that looks like an egr valve. If anyone has any other advice for me, I'd appreciate it.