My 2003 Ford Mustang V6 3.8 is struggling to start, new battery and alternator good. Any suggestions?

My 2003 Ford Mustang V6 3.8 is struggling to start, new battery and alternator good. Any suggestions?

Pull the positive ( red wire ) battery cable clamp off of the battery post & clean the inside of the clamp and the sides of the post with a small piece of sand paper. If that helps, most all car parts stores carry a small wire brush designed for just that task. Also, around when your car was made, Ford tried-out a new light-weight sheet-metal battery cable clamp instead of the "lump-of-lead" ones - They didn't work. If you have those light-weight clamps, you'll have to get them replaced with the old fashioned lump of lead clamps.