Hey guys, im new to the mustang world. I got a 91 the other day, car seemed to run good until I filled it and it began bucking. It runs fine until after about 20 minutes of driving after that it begins bucking in every gear, no matter the speed or how high its idling. I also had an issue tonight when I cranked the car it cranked very slow and melted the ground wire on the battery. Bad ground, maybe battery?