my 2c
give it a general tune up, plugs, wires, cap, rotor etc.... fresh tank of gas with some Cheveron techron in the tank, if that doesnt help, then could be a few things:
Vacuum leak, idle speed needs adjusted (idle screw), throttle cable needs adjusted for proper tension, my book says 3 to 5mm of play when warm.
the air valve in mine gave me some problems so i plugged it and it was better. it should be open when the engine is cool and closed when hot.
also, quote from book:
idle speed control (isc) solenoid valve-
40) With the engine off, unplug the ISC electrical connector and connect an ohm meter across the terminals (left upper and left lower). compare your reading with the resistance listed in the spec section. (its 5.4 to 6.6 ohms @ 68 degrees). If the resistance doesn't fall within the spec range, replace the ISC solenoid valve.
41) Unbolt the ISC solenoid valve from the throttle body. Using jumper wires connected to a 12-volt source, energize the ISC solenoid and verify operation. CAUTION: do not energize for more than 1 sec at a time, if check must be repeated wait at least 10 sec before checking again.
42) If no clicking sounds can be heard during the test, replace the ISC valve.
hope that helps, at least a place to start. have fun
