4R70W Problem, I think

Ive got a 97 F150/4.6/4wd with a 4R70W trans (according to the data plate).
At cruise speeds it seems to slip in and out of lockup when starting up a hill or starting to pass another vehicle. It happens so quickly it almost feels like it is an engine skip. I replaced plugs, wires and EGR valve thinking it was a skip, but now think it is probably in the trans.

Is there a TCC module external to the trans?
There are 158k miles on the truck but the truck has never been abused/off road and is in excellent condition. The fluid looks good, and has had regular services.
Thanks

Does it feel like going over "rumble strips"? If so, you need to flush and fill the Trans with fresh Mercon V ATF, DO NOT substitute ANY other ATF in this transmission.

Here is a "how to" article: www.crownvic.net/tech/transservice.htm

You MUST drain the T/C to do the job properly, a "flush" is not even close to good enough.

Thank you for the suggestion on the fluid change. I have a 1998 2 wheel drive F150 XL with the 4.6 V8 with 129k miles. I did exactly as the directions specified, even put the pan in the dish washer to clean. That truck now runs better, shifts smoothly and does not making eratic shifts or the "rumble strip" shakes anymore.

Thanks for the help. It was a real easy job done in one evening after work. The pan is easy to access and remove. The fluid pumped out easily. The refill went just as described. I even took the little extra time to be sure the cooler was flushed.

This is the first Ford product I have owned. My previous experiences with them were not good at all. When a friend asked for help with his Ford car, it seemed like the tools most often used were a hammer and pry bar. My mother had a mustang at one time. Finally I talked her into giving it away. The favorite tool of that car was a hammer also. But this F150 is OK so far.

Thanks for the help.