It's a 96 t-bird V8 with 146,000 miles.
I was driving from Milwaukee to St Paul yesterday. 330 lime trip, all highway, no problems what so ever. 5 miles from my house, I have the cruise set at 60, then all of a sudden the revs start creeping up and the spedo starts to drop. I shift out of OD into third. No problems there. I tried 4th again, same problem. It won't accelerate in 4th, it barely holds on to the speed, almost like being in neutral. Got home the rest of the way in first, second and third with no problems.
I drive the car today. Everything is fine. There is no hand up when shifting from 3 to 4. It is actually a fairly quick shift. Torque converter locks up fine in 4th.
(I spent most of the morning searching the forums, and most of what I found was the 3-4 shift, not so much the slipping problem described above)
I have a 98 Mark 8 with 46,000 miles that is sitting in the garage for various reasons. Would it be worth swapping that tranny into my t-bird? Just wondering if I am on borrowed time in the t-bird. If I swap the mark 8 tranny into the tbird, then I can get a build tranny for the mark 8.