cold idle problem and uncontrollable heater in 86 944 N/A

[PoPoBoy944]

right now when the motor is cool it will start right up but sometimes it will idle at 3000rpm and sometimes it will barely run (500rpm) once the motor warms up the problem progressively goes away. right now we think it could be about 4 things but i dont have the time or money to try all 4 they are a vacuum leak (checked for it dont think thats it), idle speed regulator, pcv valve (does one exist?) air flow meter, or computer. We checked the air flow meter with the gate in the meter pushed to wide open throttle for voltage as prescribed in the shop manual and got 5volts when a reading of over 8 was specified in the book. voltage also does not change whether the gate is open or closed in the meter. What exactly would this cause? is it my idle problem? also the heater in the car does not stop running at all unless it is cold outside and only rarely does it stop then. the A/C also blows hot air but the compressor does turn on. the lower vents also do not blow air. does my ac need recharging, is my heater control valve shot or is it maybe a sensor. Please send help to a kid over his head in problems, thanks!

Tom