I have a 1992 da9 with a 98 b20b swap,i was driving the car with ac and had no problems it idle at 1000,It was time for a tune up so i popped the hood thats when i notice the vaccum line from the fpr was diconnected.I went ahead and plug it in started the car and it idle like at 2 300 rpms close to stalling.I left the car on and disconnected the the line and it shot up to normal,so i plug it in andturned off the ac and it went back to normal anybody have a clue of what this could be?

 

It sounds like your base idle is off. your ecu got used to yer new driving style with a vacuum leak. turn off any accessories ie: a/c, heater, headlights, radio. etc. you need to jump the blue service connector underneath the pass side kick panel. i use a paper clip. this will stop the ecu from correcting your adjustments when adjusting the idle. yer check engine light should blink once you start it. start you car and idle until warmed up you should here the radiator fans kick on. check you have no vacuum leaks. adjust the idle screw on the throttle body with flat head screw driver. (some times the idle screw is covered by honda bond to prevent the idle screw to loose adjustment when driving.) right is close and left is to open. in your case it sounds like you have to turn left. set the idle to 900 rpm. and let idle for awhile. turn off car. take paper clip out from connector. restart the car check the idle and adjust as needed. good luck!