Occasionally, while driving down the interstate, and this usually only happens at higher speeds, my rpms begin to jump. Not much jumping but very noticeable. I'm not really sure what to think but it's been doing that for a while. I just put a new water pump in (unrelated problem) and I notice that it's still doing the rpm jump/jerk thing. Anyone have any suggestions, I'd appreciate it. Thanks!

 

could be slipping..my dads 06 had to be rebuild at 28k miles... and we got it at 26k miles