random reving at 75 mph

[miles5241]

engine will randomly rev while in overdrive when cruising down the highway i looked into what it could be but could not figure it out. anyone got any ideas? btw 96 burb with 5.7 vortec

 

[92GMC]

sounds like the transmision is slipping

 

[Problem2420]

yeah i think it maybe the tranny too.

 

[miles5241]

ok that would make the most sense. since its got a pretty bad hicup in it in 3rd gear.

 

[silverado13]

i wouldnt call it "slipping" im 90% sure its the TCC lock up solenoid, sometimes they go out completely and youll lose 3rd gear, but in your case it sounds like yours is going in and out of function, try this link, http://chevroletforum.com/forum/silverado-fullsize-pick-ups-21/transmission-gods-have-arrived-38879/, i posted it on another forum a while back, almost all of tranny probems arent internal related, you should be able to just replace the tcc lock up solenoid and be good to go