I have tried it with a/c on and off. Doesn't matter. It seems to do it more when going down a hill with the cruise on than going up a hill. I just had ford flush the trans. but it didn't make any difference. Probably needed to be done anyways.
I recently purchased a 98 sho with 98K. I noticed that the rpm seems to jump 100-200 rpm when the car is on the highway. Car seems to shift fine when accelerating. Is this the start of a trans failure:rainshit: or is it simpler than that?