I just completed a 97 ls swap into a 96 civic ex and it does't idle for crap. If I unplug the map sensor the idle is fine but then the check engine light comes on. does this mean my map sensor is bad or is there something else that I plugged in wrong or something. My check engine light did not come on at all after we completed the swap, just when I unplugged the map sensor. Please help I wanna drive tjis today thanks

 

The MAP sensor shouldn't cause ur idle to fluctuate. It really just controls how much fuel is dumped while it monitors the intake manifolds vacuum. It would really just cause ur motor to run lean or rich if it was bad. I would check ur coolant level, IAC, and TPS because those are the main causes for up and down idle. If all of those check good, take off ur intake and place ur finger over the lower left hole in the throttle body. Make sure you do it when the car is warm and if it still has a vacuum then pull off the throttle body. Remove the fast idle thermo valve and check. That is most likely the case. But in ur situation it's probably one of the others sensors when you unplug ur MAP the idle stabilizes.