Odd problem all of a sudden

[Bigdodgeram828]

Here in the past couple days while driving my truck has started this very annoying jumping up in rpm problem. Everything is fine when started up but as soon as I start down the road driving at 55-60 (even less or more) my truck will rev up to 2000rpm and then back down to 1500 about every 4-5min. It does not do it at idle. No check engine light on either.
The only thing i've had done lately is I had my A/C fixed and catalytic convertor replaced. Any ideas, kinda clueless right now since it's not throwing a code.

 

[jhemi]

could be a/c pump kicking in and out, just a thought

 

[Bigdodgeram828]

I haven't even tried turning the A/C off yet while driving, I've been enjoying it to much in the 90-100 degrees lol

 

[dth418]

you will typically see a slight rpm jump when your a/c compressor kicks on but it shouldnt be that much. I would definitly try turnign it off while driving for a bit and see if that helps out

 

[KGBIGCOUNTRY]

What did they do to fix your A/C? The compressor could be dragging causing the spike in RPMs then it falls back to normal once it spins.

 

[Bigdodgeram828]

All the guy said was there was a small leak he fixed it and filled it back up with freon. Said everything else looked good.

 

[RubberFrog]

ac.