my truck has had an issue stalling when im off the gas at low speeds -- and when im around and under 30-35mph and off the gas the volt meter drops and the lights dim and as soon as i hit the gas everything goes back -- doesnt have a problem starting back up at all just keeps shutting off on me like at lights or backing up off the gas --- anyone have an idea -- ive changed the battery but nothing .......

if the idle is getting low the alt may not be able to power at low rpm. check the throttle body butterfly for carbon build up, clean with tb cleaner.