when i redid the top of my motor and put it all together my truck has tac jump. when at a light the trucks idle goes from 600 rpm to 700. back and forth. and i just replaced everything. i never did this before and it makes me mad whats causing it

 

Possible vacuum leak.

 

but were at? i checked all the vac lines. its a very little little jump like its barly noticable unless your paying attention. but im paying attetion and i dont like it.. i checked all the lines though?

 

I have had the rpm jump on my 99 before. Actually it is starting to do it again. Last time I pulled the idle control and everything off off the throttle bottle and cleaned it all throughly and reinstalled and the rpm jump seemed to go away.

My rpm jump seemed to happen mostly when driving with the cruise control on. Sometimes I could notice it happen if I help the throttle at the same level but that happened rarely.

Hopefully this helps.

 

come to think of it my engine light came on and it was one of the sensors on the throttle body giving me trouble. ill try that thanks

 

if its jumping while on cruise control, usually is the TPS on the driver side of the TB. If it's mostly at Idle, then you can clean or replace the IAC on the backside of the TB. Also check again for a vacuum leak.

I had the surge on cruise one time and to change out the TPS takes less than 30 minutes. You only need some Torx head screwdrivers. Costs around $30-35.00

I have never had to work on the IAC but I understand that its held on with Torx's as well.. Hope this helps

 

ah thats what it is. when the valve cover was off the plug fell in oil and i must not of cleaned it off good enough. crap thats what it is.