your problem sounds EXACTLY like the problem i had with my hatch with my b18.. plus i know of numerous other people who've had it.. this always fixed there problem..

for about 10 min worth of work it's prolly worth a try.. EVERYONE always told me it was the idle air control valve i replaced mine twice trying to fix the problem..

if it's not the FITV then idk what it is.. but i think it'd be worth a few minutes at least to see if that could be the problem.