FlatBlackCoupe

I just traded for a '92 coupe yesterday and it's got an idle problem. I really don't know much about the car. It idles between about 600-800 rpm, but it's up and down as the car idles. I'm pretty sure this motor is suppose to have a MAF also. The guy that had it before me, just stuck a K&N filter on the end of the throttle body so there is no MAF. I can't tell what kinda throttle body it is and the intake is like none that I've ever seen. As far as the motor, it's been bored to a 306, 520 Comp cam, ported and polished Ford Racing heads, Ford Racing shorty headers, no a/c and no p/s. Any ideas on where to look first?