GM Repair Problems? Ask GM Repair Expert Now.
There is always that your ECM could have a faulty quad driver commanding the IAC to retract for a fast idle.The 94 had no on board diagnostics .First thing to do is reconnect everything,cycle the ignition a couple of times for a reset & look at the IAC counts on a scan tool.The # XXXXX go over 100 (high counts represent a fast desired fast idle command) & usually sits around 30-55 in drive,according to load.Look at all the data parameters TPS should be around .36mv at closed throttle,MAF around 4-7 gps at idle,fuel trim around 128 (give or take 9 counts).The ECM will raise the idle speed if it has an input from a sensor that the engine is under load.Check the wiring harness at the engine TPS,IAC,MAF for a broken wire.if necessary disconnect the harness at engine & ECM use an OHM meter ,all readings should be .002 or less (move the harness around while checking.If all look good I would suspect ECM fault.
That sounds like a bad PCM where the internal logic is correct if you can cycle the ignition & all is ok.
Input sensors are MAF,MAP,IAT,ECT,TPS,O/2,FUEL TRIM,KNOCK SENSOR,CRANKSHAFT SENSOR,CAMSHAFT SENSOR,GR POSITION SENSOR,VSS,P/N SWITCH,BRAKE SWITCH,AC PRESSURE SENSOR