[Update: May 24, 2008]
A rebuilt ECM solved the problem. While troubleshooting, I noticed that the ECM would not store the error codes. This was an obvious sign of a faulty ECM, so I purchased a rebuilt ECM. Problem solved, and rather cheaply also. This is the benefit of having skills to troubleshoot your own “equipment.” Also, it is VERY important to buy a rebuilt computer from a known reliable vendor. It seems as though a lot of these ECM “rebuilders” are not shipping properly rebuilt units.
After my original post below, I parked the car for the winter (like I do every year, from November to March.) Once I fired the car up this year, the problem was worse — the symptoms would occur on every drive. This is when I noticed that the ECM would no longer store any error codes, and would only flash “1, 2”. Hence, the problem was rather easy to diagnose once this behavior was consistent.
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(Original Summary of problem, posted October 24, 2007)
I have a mint 1993 Corvette, garage-kept, purchased new by me in 1993, with only 10,000 miles, Automatic. It has developed a problem. While driving, it will occasionally flash the Check Engine light, and sometimes (simultaneously) flash the `Service ASR` light, flash “SYS” on the LCD dash. When the problem occurs, “Service ASR” lights, the car may give a hard jerk, momentarily stall, etc. When this happens, it may be hard to keep the car running, and if it stalls, hard to restart. Let the vehicle sit a little while, maybe 20 minutes, and it will start and drive normally (like no problem ever happened). The problem has not occurred on very short trips (5 minute “trips-to-town”). Typically occurs after 12-15 minutes of driving.