Highway idle surge trans prob or other?

[soundwave2000]

Been checking this site out for a while, and figure if any one can answer this its some one on here. Car is a 96 cutlass supreme 3100, just put another trans in from 97 regal (original trans literally broke into pieces), replaced most electrical components trying to solve p0300, car runs perfect now. Only prob i have is highway driving above 50mph the engine surges, bounces between 1700 and 2200 rpm. If i take my foot off gas it stops, or if i apply more throttle. Does this in 3rd or drive, doesn't matter. Could this be a trans prob, or is it an engine prob?

[boomofdoom88]

Probably the convertor

[robertisaar]

was the regal a 3100 or 3800?

[soundwave2000]

regal was a 3100, and tc has been replaced not to long ago as well

[3400-95-Modified]

how many miles on the replaced trans and did you do an internal inspection on it as well as check over the TCC apply valve and such? Sounds like its just trying to lock the converter and keeps falling out of lockup.

[soundwave2000]

after testing things and probs with other car, i finally got back to this prob, disconnected ground wire for tcc sol and no change, so am I correct in assuming its the tcc solenoid? Dont know miles on the tranny, but did briefly inspect internals when i swapped out the side pan. everything looked good but I didnt do an intense inspection tbh.

[3400-95-Modified]

If you disconnected the TCC solenoid then no that's not the issue. It's something else if it's still doing it.