black cap on IAC

what is the black cap on the IAC valve w/ the little soft foam kinda filters in it for?

I sprayed the filters w/ intake cleaner cause they were so dirty...as well as the whole IAC Valve.

I also took off the throttle body and cleaned it all out, extended my SRI to a CAI
w/ new filter

cleaned all the electrical plugs (MAF - TPS - IAC - IATS) w/ electrical parts cleaner.

Now my rpms hang like crazy...when I take my foot off the gas and hit the clutch they go up just a hair then gradually fall to about 1800 and stay there for a good 5 seconds before it returns to normal.

What I'm trying to figure out is if those circle filters are clogged or too wet will it not let air escape and thus throw it into plenum causing my rpms to stay up?

I read that thread about the box as well, however theres a round black cap directly on top of the IAC valve...I just took the filters out that I thought may be clogging it but it made no difference so I know that's not the cause.

yeah - it snaps off