It's always a good idea to perform tests and follow the manual. I think it's an ECU because it's flashing code while running, but no code is recorded. Also that VSV is controlled by the ECU and it's freaking out. The ECU also controls the Fuel Cut RPM feature and based on a previous post you made I thought that was also acting up. Faulty input to the ECU can cause it do do strange things, but unless it's a power input, it would store code and retain it. Since it's not retaining trouble code(s) I'm fairly confident the issue is inside the ECU. Nothing special about replacing the ECU, just unplug the old and plug the "new" one in. Tim