buddy of mine has a 89 crx witha b18 swap. The idle is erratic, going up and down up and down........I had a 93 that did the same thing and I adjusted that plunger in the back of the throttle body and if fixed it, but it did not work on the crx, are there any other culprits of an erratic idle?

 

mostly likely to be the IACV..but check all the vacuum lines also. I've had this problem on like 3 or more cars and I replaced the IACV and it fixed it.

 

unplug the connector on the IACV while the car is running, then see if the idle is still erratic. If its still erratic u more than likely have a vaccuum leak somewhere