I have a 1995 Coupe with Manual Transmission and LT1 Engine. About 65,000 miles. No engine modifications other than a Petris OptiSpark and MSD Ignition Coil. Other than that engine is stock. This problem existed prior to replacing the Option Spark and ignition coil. When engine is started it idles normally at 600 - 700 RPM. After driving for short while (minutes), engine idle speed increases to 1100 - 1200 RPM. If engine is stopped and restarted, idle speed returns to 600 - 700 RPM but again after driving a little bit, idle speed returns to 1100 - 1200 RPM. I have removed and cleaned the IAC but that did nothing. Any ideas on what the problem is would be greatly appreciated