The caps in my ECU looked like new and I didn't notice any kind of leakage or smell so I'm hoping that is good to go. The main power relay is mounted right below the ECU in my truck, and that's where the clicking is coming from. Since disconnecting and reconnecting the battery, it's working normally but I have to wonder if a poor connection or bad ground there could be causing the erratic behavior. Especially when shutting that door (it's right on the other side of the hinges) resulting in the truck idling way up. Maybe a coincidence, maybe not. Not sure if there's a way to test that relay or grounding, I didn't think about that...