Problems with the Bronco 2

I have a 1988 Ford Bronco 2 with over 150000 miles on it & it's an automatic trans, not a four weel drive.2.9 liter fuel injection. But only have a few problems with. For one 4 weeks agp the starter went out and I replaced it only to have it turn over a few times and quit all together so I replaced the relay but the original one was a three prong & the one I got is a 4
prong but the clerk @ advance said just use three and not the( I) prong so I did. My 4 weeks have been trouble now the starter cable is overheating at the relay and it still will not turn over and run right any help would be great my wife wants her chevy back and I want to give it to her thanks up front HardHeaded Ford Man