Blackline99

i have a 99 6 cyl, today when i started it it stayed above 2000 rpm, when i put it in drive it its normal shift back into park its goes back to 2000...what could this be, i know theres alot of options but jst wanted some opinions...thank you

GI-Jeepin'

CHeck for a vacuum leak. When I bought my 2001 GC w/4.0l it was doing that same thing. Turned out i had dry rotted vacuum line connections on the side of the intake manifold at the base of the throttle body. If i remember correctly, one was a 1/4" hose 90 deg hose and the other was 1/2 or 5/8" hose.. I replaced both of them on my 4.0l and its been running fine ever since.