Okay well it drive a 98 jeep cherokee i dont get whats wrong. My idle sometimes it decides it wants to stay around 1700rpm. When in gear it is very hard to stop because the rev is so high when i brake it brings down the rpms but you can feel it still wants to get up and go if i put it in neutral when its doing this the rpms jump to 1700rpm it will only stop this if i rev it. i dont know what to look at or what to do. Im sorry so vauge but i dont know how else to put it. Just a few months ago i replaced the tps and did the neon injector swap about two to three weeks ago. Thanks

 

Probably gonna be your Throttle Position Switch and or your Idle Air Control Valve. Both are located on your throttle body and control various fuel related tasks. My bet is a combination of both. Good Luck!!

 

Clean you IAC, reset the ECU, and see if it fixes your problem. If not, you have a bad tps or a large vacuum leak.
http://emeraldgreen97.wordpress.com/...g-of-4-0l-iac/

 

Figured it out thanks guys it was right infront of my eyes it was a vacuum line.