First of all, welcome to the board. Second, you may want to make your post title better so people will look, read and help you.
Sound like previous owners used to slam doors and hang on them when they were open. Worse if it is a 2dr cause they are heavier. You may need new hinges. Not sure if you can just replace the hinge pins on these cars. You could check with Ed Morad and see if he has some low mileage door hinges you can swap out.
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03 GT, STB, GM HD sway bars, 35% tint, GE893(37watt)fogs, Flowtech Terminators, 180 T-stat, ZZP DP & PCM, Ceramic PLOG & Crossover, 18" glasspack, 2007 17" Mustang Bullits 235/55/17 Pirelli PZero Nero, 12" R1 D\S rotors, gutted air box, GTP radiator