tvengineer

93 4.0 that intermittently surges up RPM's on the highway when driving. For example driving at 65-70 rpms at 2000 with no change in throttle or load jumps to 2500. Sometimes it will go back down then back up. Pedal response seems normal. This can prove to be a mileage killer.
Where to start looking?

Bustedback

Do you have the A/C or defroster on while this is happening?

Jeepola

There's this thing called "Over Drive", and it's normal. All cars have it. The RPM's rise when going up a hill, especially while going highway speeds.

Bustedback

I just read the post again. Your torque converter clutch is unlocking and locking. Mine did this until I changed the transmission fluid and cleaned the junk off of the valve body.

tvengineer

Nope not just normal overdrive shift. Jeepola, guess you would actually need to experience what I am describing. Flat highway, no extra strain on the engine . I think the torque converter sounds more logical. No AC or defrost not on. It's sometimes a quick shift up and down. Fluid change sounds in order.