engine's rpms go up and down while driving

[mike the spike]

ok guys, i'm new at this, but here is my question. i have a 92 5.0 and the car has 110,000 miles one, but still drives strong. this car is my daily driver and it hadn't given me a problem until now. i was driving from california to texas and midway it started doing this. i get to around 55 to 65 mph and then my engine kind of revs up and down while i'm driving steady. the rpms go up and down but that is all that happens. what can be causing this? my best guess will be something with a vaccum, but i don't know where to start. let me know what can be going on with this, and if it is safe to drive back to california? thanks, mike.

[Zim]

is the clutch slipping at all?

[MonteCitan]

if its auto, lookout... could be a bad converter lockup or a failing internal component, check the fluid level first

[mike the spike]

no, the clutch isn't slipping, its just driving regular, the engine just idles by itself, and then it goes back to the regular idle while i'm going at 60 or so mphs. its weird to explain. it almost feels like it is going to kick into passing gear and then it just goes back to normal. but i'm not giving it gas, thats the thing, i'm just driving regular and it does this. ok if it is a bad converter lockup, how can i know, and where is this located? so more than likely it is going to be a transmission problem?

[Zim]

TPS maybe?

Thats weird...

[fast64]

TPS would probably cause problems through the entire rpm range though.

[MonteCitan]

if you have an automatic transmission : yeah I'd say you've got a trans issue, it doesn't sound like its much of a mechanical issue unless your OD band is fried, or your converter is having issues..

that's just me though.. diagnosing at the counter, without diagnosing the vehicle