So if im crusing flat highway @ 50-55mph my RPMs will be at ~2200; suddenly they'll drop to 2000 then back to 2200 then back to 2000. this may go on for miles.

replaced and cleaned the Mass airflow sensor,
What else could be going on here?
Otherwise, when accelerating its fine
97 f150 4x4 4.2L

thx
Frank

 

Is it manual or automatic?!

 

If you have an automatic transmission, it's normal.

 

Torque converter?

 

have you checked your eyes?

 

Torque converter locking and unlocking.

 

it an automatic. Thats normal?? Really??
seems odd..

 

sounds like the answer you get from a shifty dealership...

 

Well, those are the symptoms of the TC locking and unlocking. Whether it's normal or not can be debatable, it *IS* normal to some degree. Try driving it with the OD off at those speeds, what does it do?