Quote Originally Posted by Tank View Post
...torque converter could be unlocked...
My thoughts exactly. Sounds like the converter isn't locking. When you lightly press the accelerator pedal on the freeway, do the rpms climb a bit??? But you really don't notice the vehicle acceleration to go along with the increase in RPMS?

I am also guessing not tuning has been involved, so it is purely in the transmission. Maybe the TCC solenoid has been messed with? Internal wiring harness may be to blame? If the TCC solenoid was not plugged in, I am sure there would be a CEL.