car has trouble starting, what could it be? Options

[6strngs]

yeah, I've pretty much noticed this since a little before I got the car, but when I go to start it up after it's been sitting a few hours, it'll start, and the RPMs will shoot up to where they are supposed to, but when they come back down, they don't stop at 750 or whatever idle is and keep dropping until they reach zero and the car dies... so I'll start it back up, and in order to keep the RPMs up, I'll rev the engine. but as soon as I let go of the gas they drop real low again, so I rev again. usually, once I rev it to ~6000 and let it come back down it'll idle fine and then run fine for the rest of my trip, and if I shut it off for a while and come back, it'll be fine. but if it sits for 6 hours-ish or more before I start it up again it'll do it again...

what could be causing this?

[6strngs]

alright, I tried figuring out what was going on a few minutes ago... well, I was checking for vacuum from my PCV valve (I think that's what it is... the little nipple sticking out the side of the valve cover) and when I pulled the hose off of it, it made a strange squeeking noise, and when I put my finger over it, I could tell it was blowing air out, but after removing my finger I saw that it left an oil residue on my finger. is that normal? I have this valve going into both my intake and that nipple sticking off the throttle body, for some reason I'm thinking that blowing oil into an intake would be a bad thing...

When I pulled off the throttle body to inspect the IAC, I did notice it was really dirty inside the throttle body and intake manifold... could this possibly be severly damaging my engine by blowing oil into the cylinders?

I wanna pull off my valve cover and see if I can get a better look as to what is going on. I've never done this before, is it hard? and does it need a new gasket when you put it back on? the only time I would really have time to do this would be tomorrow morning, but I doubt I could get a new gasket by tomorrow.