I have had this problem for a couple months now, when I use cruise control on the highway above 60mph, the tach jumps 200-300 rpm. I doesn't do this if I cancel cruise and try to hold the same speed with my foot. The truck barely goes faster when this happens. Has anybody ever heard of this before?

 

SOUNDS LIKE A BAD THROTTLE POSITION SENSOR

 

start with getting a new tps.....sound like the static from the tps is making the ecm lock and unlock the trans.....at least this is the first place i would start.....fyi take the old tps out slowly and pay attention so that the new one goes in the same way...

 

Rather than swapping sensors, head to your local FLAPS, such as Auto Zone, and have them run a diagnostic. They will do it for free and it's much more accurate and less nerve wracking.

 

a noisy TPS probably wont throw a CEL. and may not show up on a diagnostic check.

 

correct....the ecm will look at it like you laying into the throttle a little....

 

Thank you all for your help...I will try that this weekend

 

really tps, could be tqc slipping maybe? would a torque converter slip throw code?

 

yes ,a bat TPS will cause the the T.C. to unlock momentarly .the computer thinks it'a in WOT.that will make the rpm's jump 200-300 . A bad T.C. should throw a code.