I just purchased a 2006 limited convertible Silver Blue and it is amazing, best car ever. However it started doing something weird --- When I accelerate the driver side headlights get brighter and when I decelerate it goes back down --- any Idea what it could be?

 

my bet is a voltage regulator or alternator issue. Think about it. Your revving up, the serpentine belt is spinning faster, spinning the alternator faster, increasing output so I think at low revs you've got some degradation in the alternator brushings or the volt regulator is not keeping it at proper levels. I'm not an auto electric expert by any stretch, but I think this to be the most logical place, and may have something with the battery too

 

Just the drivers side headlight does it?

I would guess a wiring issue, poor connection, loose wire?

If it all lights I would say Mark nailed it.