Definately a change in voltage causing the problem. Dont waste your time and money, take it straight to a auto electric place, they can test the battery, VR, and ALT and determine whch one is causing the problem. Or you could take the DIY approach, and buy a new VR, then if the problem still occurs, buy a new ALT, then if the problem still occurs, buy a new battery. Actually Hayden, I think the VR is a mecanical device that can be adjusted. Search for posts about it. I remember having a problem with my VR on my 1st 240. I replaced it with a modern transitorised one, and never had a problem again. My Honda has a similar voltage drop at idle (the headlights dim), but i expect thats pretty normal. As soon as you rev the engine the headlights are back to full power.