I've spent 2 hours reading about OVP relays, and haven't seen a problem that sounds just like mine. My car starts and idles perfectly. Something seems to be kicking it into Limp Mode occasionally. Turning the car on and off several times usually solves the problem... until the next time.

I also gather that the OVP can trigger a lot of different symptoms, so I'll look into it further. The shop that did the wiring harness a few days ago has the car again.

I saw one posting where a guy had a similar problem and it usually reared it's ugly head after he drove for a while and then parked it. He thinks the heat buildup in the engine compartment contributes to the problem... that's why when he gets in the car an hour later, the problem shows up.

Is that the thought behind removing the bottom engine cover?