pearson7156

I have a 98 grand cherokee that when i shift into either park or neutral the RPMs shoot up. Also when driving down the street the RPMs go up and down and the throttle will stick at times. Any ideas on why this might be happening?

dave1123

Welcome to CF!

Check for a dirty Idle Air Control or a vacuum leak in the MAP sensor hose.

pearson7156

Thank you, I'm kinda new at this what is the MAP sensor hose or rather were is it located.

dave1123

Okay, the Manifold Pressure Sensor (MAP) is located on the end of a hose that goes to the maniold near the base to the throttle body and is mounted somewhere near the rear of the engine near the firewall or on it. It sends information to the PCM and coupled with the throttle position sensor, sets the mixture ratios. A leak will cause a high idle and stumbling on acceleration and surging while at speed. You might want to check the crankcase vent valve hose as well. That goes to the top of the valve cover.

Also, the piston on the Idle Air Control may be dirty and hanging up. If the throttle is actually sticking, you may have broken strands of wire in the throttle cable.