2001 1500 5.9 4X4 98,000 miles. Truck surges under normal acceleration from a stop. Accelerates smoothly if I gun it, but otherwise it surges up to about 15-20mph where it settles in and runs quite smoothly across the rpm range. Shifts smoothly - idles and starts just fine.

Replaced Fuel pump twice recently and do not feel this is the cause. Replaced plug wires and all ignition parts recently as well. Could the throttle body be the cause, as in dirty TB? Any sort of fuel flow sensor I should know about?

Any suggestions on how to proceed would be appreciated.

 

I would suggest replacing TPS and clean IAC.

 

TPS and IAC are what parts? Capable but somewhat ignorant - the story of my life. But thank you for your reply!

 

Clean IAC and check before replacing TPS....just to keep from throwing parts at it. How is your plenum?

 

Did you route the plug wires per the Tech Service bullentin?

 

IAC is on back side of the throttle body. It controls bypass air to idle the engine. If it is misbehaving, odd things ensue.

TPS is on drivers side of throttle body. Can test it with a meter. Center wire (I think) is signal back to PCM. Voltage should be less than 1 at closed throttle, greater than 3.5 at wide open, and progress smoothly. If it jumps around at all, replace it.

 

What is the IAC? What is the TPS?

 

Idle Air Control and Throttle Position Sensor.

 

IAC only controls the idle when your foot is off the gas pedal and the throttle plate is closed. it "should" have nothing to do with acceleration.

TPS can cause surging at idle or acceleration or steady throttle.