Cadillac Repair: 1995 CADILLAC ELDORADO AFTER THE TUNE UP, eldorado 8, cadillac eldorado

Question
I have a 1995 Cadillac Eldorado 8 cylinder (I think it's a 4.8 engine size). Had a major tune-up 12-05 and a spark plug/air filter change in 12-06. Since Apr. 07 the car had been running very, very rough with massive amounts of loss gas mileage. Decided to get a diagnosis and they said I needed a major tune-up. Got a tune-up and put in $20 worth of gas for measure, went 50 miles and the gas was out. Noticed a check engine lite on, so took it back to diagnosis and they said that my Idle motor was out. The shop person was very rude after I asked him twice what that component was and what it did and how is it affecting my car. Is there anyway you can help me with a symptom diagnosis and on what this Idle motor does?

Answer
All the IDLE SPEED CONTROL MOTOR does it to maintain the engines idle speed so the engine will not stall.

Lets see what fault CODES you have:

1. Ignition switch ON, Engine OFF.

2. Simultaneously push and hold the OFF and WARMER buttons on your climate control panel for 3 seconds and release them.

3. CODES will appaer in the form of a combination of letters and numbers and the word CURRENT or HISTORY may appear as EACH code is displayed. I need this word also as it appears on the display.

4. Write down the codes EXACTLY as they appear on the display as if you were video taping them.

5. When the display stops displaying letters and numbers