2001 Ford Mustang choking engine when headlights are turned on?

Have a V6 mustang that runs great in the day but at night when I turn on the headlights the car starts to choke out and sputter until it will not run at all. If i turn it off and keep the headlights off it will return to run good.

Weird… Runs good until the lights are on… Try this - Ford's are famous for corroding the INSIDE of the positive ( red wire ) battery cable clamp. Pop that clamp off the battery post & scrape both the inside of the clamp AND the sides of the post with the blade of a small pocket knife. Put it back together & see if theat helps. If it runs better, most all car parts stores carry a small wire brush designed just for that job. Get one & do both of the clamps, then keep it in the glove box until the next time it needs a cleaning. Also, around when your Mustang was made, Ford experimented with a light-weight sheet-metal battery cable clamps, instead of the old fashioned 'lump-of-lead' clamps - They didn't work. So if you car has those sheet-metal battery cable clamps, you'll have to get them replaced with the old fashioned kind.