This happened tonight and kind of freaked me out. When I turned off the lights, the idle just starts surging and becomes erratic. When I turn the accessory lights back on, the idle returns to normal...

What could be causing this?

Any help would be appreciated!

 

Did you give the idle air control valve a check ?

 

I will give that a try. It can be affected by the turning on and off the lights?

Thanks!