At 70 mph and about 2000 rpm, I have noticed that when i lightly press on the accelerator, the rpm will rise but speed will not increase. i press a little harder and the rpm will come back down to about 2000 rpm. Transmission fluid and filter were recently changed so levels are good, but there was no change in behavior. Mechanic did mention that the fluid smelled a bit burnt. This is a rebuilt transmission.
Any ideas what could be happening? I suspect the transmission is going out again.