help! i have a problem in the mid rpm range with my truck jerking. it acts like the throttle is over sensitive. dont want to throw a bunch of money at the wrong parts.any input would be appreciated

My first guess would be the TPS on the accelerator.

Would you describe it as similar to the tug on a fishing line when the fish 1st hits it? "Fishbiting" hesitation/stumble under load is sign of fuel delivery or timing problem. Try driving in that range again in cruise control, this will take the APP module attached to the accelerator out of the control loop, report back might have some other things to look at. When was last fuel filt change? Edited by: Turbine Doc

it's not so much under a load as it is just driving around town empty.as far as the "fish biting" it is more violent than that sounds to me.this truck has done this since i have had it.took it to a chevy dealer and they put a new pmd on it.it didnt change anything.my cruise is inop at present but it acts like the problem is directly related to the accelerator pedal

The Fuel Solenoid is going out. If you have a scanner with CT count it might show greater than normal readings. The solenoid will get worse untill the armature plate has broken free of the retaining screw. It takes a special guage to set the armature travel, requiring a rebuilt replacement. cruise control wont work with a bad PMD, or a bad fuel solenoid. The dealership has the scanners to catch this.Edited by: quantum mechanic

If you have it like mine had it, it does this jerking thing at about 45 MPH, or so, and only for a few miles an hour band on the speedo too. With the check engine light on (if that's the case), and no cruise, I'm suspecting that the optic sensor on holiday? Got any codes read off this thing? or is the engine light not on?

no codes .got a friend that works in a diesel shop.he's going to use a scan tool to see what he can find out.will report findings

Injection pump is bad, time for replacement.

scaned it last night. no codes .must be something mechanical.i'm thinking about new injectors because of the amount of black smoke it puts out. any input appreciated.