46RE Shift Points

I recently purchased a 71' Dart Swinger that has a 01' 5.9/46RE swap in it, and I'm trying to figure out if I have a transmission problem or if the ecu has been monkeyed with. I know that in the past the car was used at the strip on occasion so perhaps it maybe a combination of both.

What I'm experiencing is that the shift points seem to be very high in the powerband. I'm not hammering it, just accelerating normally. It won't shift into 4th unless I either take pressure off of the gas pedal or hammer it, then it shifts abruptly. I'm not expecting a smooth shifting transmission due to its age and mileage (which I assume is high), but I would expect a little better performance.

The other issue is when its cold, it barely gets out of 1st gear. As it warms up it begins to shift normally with the exception of what I described above. I have an idea of what's happening and its going to the shop next week, but I'm hoping that someone here can shed a little light on what I'm dealing with.

Thanks