After doing a lot of research on several Prius forums, I discovered that my problem could be cured by replacing the ECM. The 01-03 ECM can't be re-flashed like the Gen II and up can, so a replacement ECM was the cure. The cost of a new one was anywhere from $700.00 to over $1000.00. Under $100.00 was a GREAT deal and it solved my problem.