Acceleration

It sounds like the torque convertor clutch lockup solenoid (TCC) is stuck in locked position. It should only lock at a certain speed, and unlock as engine load increases or brake pedal is depressed.

Was anything done prior to this occurring?

What is the idling speed?

When was the last time a tune-up was performed?

Do you have any overheating or coolant losses issues?

Have trans shop diagnosis.