have an idle problem need help

[k-custom]

my civic has the d15b7 engine well at idle it surges from 900 rpm to 1500 rpm but it run and drive good sometimes when you rev it high then let it idle it wont do that for 30 to 40 seconds. ive checked for vaccum leaks and checked my iacv, i unplugged it and the engine rev up alittle high so that tells me its fine any ideas on what the problem could be?

[89crxz6]

timing?

[thsmrtone1]

what size injectors do you have and what form of engine management... or is it stock?

if its stock then are there any CEL codes?

if no CEL codes then check for any loose hoses on the IM, check the timing, and check the IACV (i remember there being a write-up a while back on how to do this, but i cant remember where it was... someone might chime in)

[transzex]

FITV or IACV

[xX98CivicCpeXx]

mine does that from time to time depending on temp

[transzex]

kill him!

[BLACK-KNIGHT]

take off the iac and clean it out

[k-custom]

everything is stock for now but i dont get it no codes no vac leak cleaned injectors even new pvc, iac works i don a diagnostic on it checks fine. so what is the fitv? where is it located? close to the iac? please ppl i am greatful for all of your help so please anymore ideas or suggeustions would be great