My Borg Warner CPS would run fine at low rpms and freak at around 4000. It didn't matter if I was full throttle or not. If you can accelerate full throttle until 3500 to 4000 before the problem begins I'd take a look at the CPS. Perhaps it got pulled or tugged during the wire instal causing a bad connection.

If not the CPS I'd take a look at the alternator too. Not enough juice and weird things start happening. Eliminate what you can without spending $$ and soon you'll find the why.

Les