I have a 97 Integra LS with an S4XA automatic transmission that has 124k on it. Once it warms up, the car will not shift from second to third. I have to accelerate hard in second and then ease off to let it shift into fourth.

I replaced the fluid, but did not have it flushed = No effect.

Acura dealership says the clutches are slipping and I need to replace the transmission. I just bought a used transmission. However, the Engine Check light came on last week and I found the following codes:
P0700 Transmission Control System Malfunction
P0715 Input/Turbine Speed Sensor Circuit Malfunction
P0730 Incorrect Gear Ratio

Any suggestions?

PS Is the old transmission core worth anything?

PPS I bought the car used from a Toyota used car lot.