I have an b20 vtech motor i just added an 68mm tb on it and it started to idle wierd.When i would unplug the map sensor it would idle normal but when i plug it back in and turn the motor off and back on it would start to idle wierd again.

 

either your map sensor is bad or play with the idle screw, if you unplug the map sensor the car should run worst than it was originally.

 

i tried adjusting the screw and it didnt do anything and when i swaped over my gsr tb and used the same map sensor it worked.I checked for any vacum leak and adjusted the tps sensor to .45 and it still did the same thing.My car sounds like its miss firing when its at low rpm but when im at around 4 grand it runs great