OK, here's my problem.
1991, 1.8 liter Plymouth Laser.At idle the engine rpm hunts up and down between about 1000 and 1500 rpm. After about a week of driving, it seems to settle down at about
700 rpm. There is no problem will driving the car, pickup is good, and there is no sign of throttle hunting, the tach has a constant (but maybe higher than normal) reading. It's only when the clutch is depressed or the car is in neutral that we have this problem. There seems to be a cycle of three swings every 5-8 seconds. On the down side of the last cycle it seems to drop slower than on the previous swings c. This is really pronounced after the battery has been disconnected, sometimes. The idle position sensor tests ok at idle, closed at idle, open when off idle, and throttle cable is lose. The throttle position sensor test OK, 5k ohms, in spec, according to the service manual (I can watch the resistance change as the throttle is changed). The throttle motor position sensor varys when the engine is hunting. As well the static test shows the resistance of the sensor(about 5K ohms) is within spec. Didn't try the portion of the test that calls for energizing the throttle motor though. No check engine light.I've emptied two cans of ether trying to find a vacuum leak, no luck, no leaks.
I've run out of ideas, any suggestions??