Ford F150 - Increased idle and shifting problems...NEED HELP!

First time poster...2002 F-150 Supercrew FX4...120K miles...AOD tranny.

This has been going on for about two years and haven't taken the truck in because I am betting that I would have to pay them to tell me they can't find anything wrong and hasn't been convenient to go to the repair shop when the problem occurs.

I drive about ten highway miles to work everyday. During wet conditions (rain or heavy dew) the truck runs/shifts fine until I slow down for the stop light. The tranny then downshifts noticeably and rpms stay up...have to hold the brake pedal pretty hard to keep vehicle stopped. If I put it in neutral or park the engine will idle at about 2,600 rpms. Of course I try not to do this since putting it back in gear is a little rough on things. Turning the engine off does not cure this. If the tranny goes down to first gear, it won't shift to second without manually shifting down to second. It goes into second then with no trouble. To get it to shift from second to third and third to overdrive, I must move the gear selecter to overdrive and accelerate quickly and/or run the rpms way up to get it to shift. If I can get it to go all the way to overdrive, problem solved and everything functions normally and very rarely occurs again during that drive (sometimes a little difficult since I have to get it up to 65 or 70 mph to achieve this at times). This does not occur everytime there is moisture but wet conditions seem to be the one common thing I can see.

My thoughts are that this isn't likely a tranny problem but something to do with the rpms going up which then causes the shift points to change. Since moisture is involved, I also assume this is something electrical. Could it possibly be related to the cruise control???

Any advice or ideas are much appreciated.

That is strange. I would start by checking all the vacuum hoses for leaks.

Isn't this a computer controlled tranny? It's possible one of the electrical connections to it is loose or dirty... unplug the connection(s), inspect, clean if needed, apply some dielectric grease to keep out moisture, and plug it back in.

Not sure if it will help or not, but it should only take 5-10 minutes and the grease can be had for under $5 at any auto store.

Thanks for the suggestions...I will check out the connections, then wait and see.

Electrical problems can be a pain in the ass if the problems only come when it is wet out you might have an issue with the MAF sensor which dose alot of configuring like idle speed and even load reading for tranny. Alot of times you will not get a light on this malfunction but if you can get it on a scanner it should let you know. I is about $100 for a new one so you dont want to just repace it even though it is really easy.