If your having a problem with the Idle Speed Circuit, there is one easy way to find out. Hold the gas pedal about ½ way down, and start the car. The engine should fire up. But when you take your foot off the pedal, the RPM's fall at a normal rate. Only now they will drop down to 0 and kill the engine. It sounds to me like you have a bad ground connection. I did have a problem with a wire that went bad in the circuit. But I don't think you are having the same problem that I did. You said before that you grounded the connection, and everything worked ok after that. So this sounds like you had the problem already diagnosed/cured. I am curious though as to where you grounded the connection at (I'll explaine why). Now, there is one more thing. The microswith doesn't just turn the Idle Speed Circuit on. It also activates a small solenoid on the back of the engine. That's why there is an inline diode to prevent feedback (section D:05:02). What is tied into this circuit is a vaccum solenoid. The EXACT operation of this solenoid and it purpose, I'm honestly not 100% sure. I think that it kills that vaccum connection between the distributor, and the thermal switch to prevent enrichment of the fuel durring idle. In other words it kills the vaccum to the Control Pressure Regulator. Although the lines do also conect up to the engine. But since it is tied in a way to both your problems (vaccum/engine performance & idle speed electrical connection), it is something that you will want to investigate. I would reccomend that you first call your friendly DeLorean vendor for a complete explanation of the circuit, as well as a diagnosis. Perhaps the 2-prong connection on the back is dirty, and just needs to be cleaned. I hope this helps you track down your problem by shedding a little more light on the subject w/a differant angle on things. -Robert vin 6585