Low, loppy idle then too high, then low again....

[Fox Body]

Hey, the GT is not doing bad, but the it's having a little problem.

1) When I first crank it after it's been sitting for overnight, it really wants to shut off if I allow it to.

2) After it has warmed up, it doesn't idle well. It'll idle high (~1100 rpm) for a few seconds, then idle low (~ 600) in a loppy kinda way (like a umh, umh umh, instead of a smooth ummmmmmh).

3) Also, if I'm driving down the road and come to a light it'll idle high like mentioned in 2), then low, then high... even when I'm driving and am slowing down for a stoplight, if I depress the clutch pedal, it idles high (above 1000) and then after I FINALLY come to a dead stop, it'll drop down, but hten go up then down , etc (as already mentioned)

Just to start off with easy things that I know haven't been recently changed anyway, I put in a new fuel filter and spark plug wires (trying to start off with the easy stuff).

Could I be losing vacuum somewhere? What is the hose that comes out from the inside of the cavern of the upper intake (directly above the lower intake)? There are 2 hoses. The smaller one on the left (if you are looking at the intake from the front of the car) seems to be old and almost corroded. From the intake, I think it goes to a plastic junction that then goes to that smog canister. It's not easy to get to that's why I haven't changed it yet.

Any ideas guys??? I don't really care for a ruff idling car........