91 awd turbo sport sedan starting problem

im about to buy a 91 sport sedan with 118k but it doesnt run the owner says that it would run until it made a loud squealing/screeching noise and now will not start at all , it turns over but will not start , owner has told me it only does it sometimes , he thinks that it would be the oil pump or tran flex plate? can anyone help?

so it only doesnt start sometimes? hmm...have you checked the timing belt or any of the belts for that fact?