Cadillac Repair: 92 Cad Deville, rotor coil, mixture control

Question
I have a '92 Cad Deville with 170,000 miles on it.In general it runs great.When I got it 10,000 miles ago, I put in new plugs, wires, cap and rotor, coil. It ran great for a while then started ghaving idle problems. It has a new Throttle body position sensor, a new idle mixture control valve and as recommended by a mechanic, a new computer. It idles low enough to die from time to time. Idle won't kick up for cold start, and I get "e30" code(Idle speed control circuit).It also has a new fuel filter and fuel pump. What else could be making it not idle correctly?  

Answer
Hi Mike, The problem with the lower idle could very well be the idle speed control motor/ISC. When its at the minumum position the idle speed could be around 500rpm and if it isn't adjusted propperly or the idle speed isn't relearned correctly after disconnecting the battery you might not even have to use the gas pedal to drive 30mph. Your mechanic if Caddillac savvy should have been able to output cycle or make the computor move the ISC in and out to see if it is stuck. I would say that if it is the original one that came with the car installing a new ISC and adjusting it will bring your idle speed back to where it needs to be.

    Let me know if you need anymore help. Bill