'92 Eagle Talon TSi AWD Idle Problem

Okay so, my talon has been acting up for a couple days with "Erratic Idling" i has use an oil treatment to see if it would work but it did not.
When I start my car i notice that my oil gauge peaks to about 100 psi and slowly but surely reduces to zero (might be normal since its getting colder here). But ass soon as my temp. is up and my oil is at a fine level my idle goes... it idles back and forth between 700-900 rpm. just thinking that it might be my IAC (idle air controll) motor but cant be for sure. Just thought i'd ask for help before i take it to "Crap Tire" tomorrow..( just to get it checked don't worry :P)


P.s- My boost guage goes up a little on the stock gauge and just by a millimeter or so on my aftermarket gauge, as it goes into a low idle