Okay.... I got it out. Here's the trick.
Remove the Cruise Control servo to get access to the ECU connector in the engine bay.
Remove the cable connector in the engine bay using a 10mm socket.
This step may not be necessary:
Remove the two 11mm captive washer nuts on the 6mm-1.0 studs, one just above and one just below the ECU in the engine bay. Mine were cinch nuts and came off hard.
Remove the unrelated forward connector and cable that is next to the ECU under the dash to gain clearance for the ECU metal support bracket to drop down.
Get your hand between the ECU support bracket and the firewall, pull it rearward, and wiggle/rotate the ECU and the metal support bracket back, down, and out.
I tried doing it without removing the metal support bracket but was unsuccessful because the ECU would not rotate down enough to clear the obstructions under the dash, and, the ECU would get hung up at the opening in the metal support bracket on the engine compartment side.