It was an Autologic chip on a stock Mustang computer. Worked fine for 2 years/approx 4K miles. One day when I was driving up I85, the check engine light came on, and the car started running rough. It still drove, but was running really rich (clouds of fuel). Checked all of the sensors, ignition, etc. Basically, the computer was bad. The computer would work ok sometimes and other times it would crap out. I switched to AEM and have no problems now (except for tweaking the damn cold start table).
From what I understand, Autologic chips are pretty poor quality to begin with.