Yep, sounds like a bad VR. Since it is usually intermittent, verifying the voltage (spike) can take some time. I found that using an old cell-phone car charger cord works well for real-time voltage monitoring. You just cut off the phone end, strip the leads and crimp on connectors to plug in to your DVOM. Then you can just plug the other end into the cig. lighter, and monitor the voltage from the driver's seat. If the stereo cuts out, and you see something like 17V on the meter, you have found the problem.
