Checked out a 1998 mustang gt today, thinking about buying it and I was just wondering, what rpm should a automatic nonpi 4.6 should shift at? When I was test driving the car going into 3rd gear while getting on the freeway it shifted in the mid 5k range at full throttle. That seemed a little high to me, like maybe it was slipping, but I had a 94 5.0 which stock I thought optimal shifting was in the high 4k range, so I could be wrong.