Pulsing at highway speeds?

[EastTXYukon]

Let me start off by saying that I'm not the most mechanical guy around.

I was hoping y'all might have some ideas as to what is causing my 96 yukon to pulse at high speeds. Cruising steady at 70 mph/1700 rpms, my truck will intermitently jump about 300 rpms, then return back to normal. It does this off and on till I exit the highway.

Tonight, I got on the interstate, truck ran great, then I exited after about 30 minutes to get some food. Drive-thru, return to the interstate and get up to speed and the pulsing/rpm jump starts happening. Up until this point, everythig was doing just fine.

Any ideas would be appreciated before I take it to my mechanic

[h0tr0d]

I'd change the trans fluid and filter first and see if that is the problem. If that doesn't help, it kinda sounds like the torque converter is having some issues.

[jmyler]

I'd change the trans fluid and filter first and see if that is the problem. If that doesn't help, it kinda sounds like the torque converter is having some issues.

I second that. sounds like a tranny issue. check the fluid a lot of times it might just need to be topped off.