well its an 88 integra LS..i put a newer/used shortblock in it becuase the the head gasket blew on the other motor...it starts up and runs alright, little rough, but after it warms up for about 15-20 min when i come to a stop the idle starts jumping from 500-1500 rpms back and forth. it seems have something to do with the engine temp because if i drive it for a little bit after it starts the weird idling and get the air circulating again, when i stop it takes about 30sec-1min to start the jumping idle again.....

im not getting any check engine codes, and ive searched around for obvious things like vacume leak and stuff like that and cant find anything....any ideas? thanx

 

up for the question!

 

you can try reseting your ECU, this may or may not help.

 

up

 

remove throttle body. clean. reinstall throttle body. if problem persists, check iac. when reinstalling throttle body, be sure to follow correct procedure to bleed coolant system, as air bubbles can cause similar problems. while throttle body is removed, replace all gaskets. gaskets dry up and shrink overtime, cause really weird driveability issues.

 

did you check the FITV?