Mercury Tracer, 1994, 1.9L, loping idle

118,000 miles.

When the car is in park or neutral the idle on my 1994 tracer lopes from about 500 rpm to 1200 rpm. If the car is in drive or reverse, the car idles a little rough at about 1000 rpm but it does not lope. It only lopes without a load.

The car was tuned up before I bought it and we checked and gapped the platinum plugs (0.054). Wires are ok.

I changed all loose and damaged vacuum hoses (most hoses were leaking or brittle), new pcv valve and installed a new temp sender for the temp guage. The ECT was not changed.

The EGR valve and EGR vacuum circuit passed all tests.

I have a Scantrol with a Ford cartridge. The KOEO tests (fast and slow) came back ok, ie. Returned a 111 code. The systems monitored while the car is running are within specs, ECT, EGR, IAC. MAP, O2.

I get a 412 and 411 code when I run a KOER fast and slow test. I got the sensor test specs from a Mitchel manual and the Idle air control solenoid passed all non-pcm related voltage, resistance and short tests. I was looking for the 60 pin connector for the PCM, but I am afraid it is behind the instrument cluster. I did not get to the throttle position sensor.

Is the 60 pin cable for the pcm behind the instrument cluster? My basic problem is where to go from here? One other note, I can stop the loping by holding down on the pedal slightly. I can put just a light amount of pressure on the accelerator to boost the idle up to about 850rpm and the loping will stop. Seems like the TPS is a problem, but would it give a IAC fault? What circuit causes the rpm to increase in drive that would override the TPS at idle?