i have been chasing a surging idle problem and got to wondering if the throttle body wasn't fully closing at idle, and the racing idle was caused by air passing right through the throttle body. to test, i disconnected the hose to the IAC...plugged it with my thumb and also plugged the inlet that the hose came off of on the intake hose. the engine continued to run quite well! i was expecting it to stall. i then took the TB off the car again and looked at the plate, and you could see daylight around almost the entire circumference of the plate.

question: should any air pass the throttle plate at idle or should the engine solely be supplied by the IAC? and...if the throttle plate is at idle and the IAC hose is blocked, should the engine stall?

i noticed that the setscrew that determines where the throttle plate comes to rest was almost full extended. im wondering if someone continually raised that to compensate for a clogged TB?

i saw some info in the FAQ about lowering that setscrew until the throttle plate is fully shut, and then raising it 1/4 turn. and from there adjusting according to the FAQ adjustment for an LH 2.4 base idle adjustment.