Problem idling while coasting

[Donovan Maxwell]

I'm having a problem with my GA16. Anytime I push in
the clutch and leave the shifter in gear, my engine
idles around 1500-1600 RPM. Problem goes away as soon
as I take the shifter out of gear and let the clutch
go up. My car was in the body shop for a bout 5 weeks.
I've only had it back for around a week now. All I
have done recently is change the oil and front 02
sensor. I'm using a Fram oil filter and Valvoline
Maxlife. The o2 sensor is a cheapy Autostoned sensor.
I'm about ready to go get my refund on it and get and
OEM sensor. Atleast I know it will work. A little
while before the car went into the body shop, I
advanced the timing to 12 degrees, but the car didnt
show any signs of the base idle being off. Does anyone
have an idea of what the problem is? The clutch does
need to be replaced, so I think it might be that the
clutch isn't correctly engaging/disengaging. I would
greatly appreciate any help. I decided I'm not gonna
sell it to get the SE-R... too many Honduh people
saying my 1.6L cant beat them... pissing me off. The
sooner I can get these little problems worked out the
sooner I can start modding more and whoopin up... I
figure this is the ultimate sleeper. No one is gonna
expect that I can take them with a "only a 1.6L".
Should be good times ahead...