If you had replaced the fuel filter and there was a negative response it may be due to the power fuel pump. If you have the self contained pump and filter unit that was available after 1988 the pump may have been overtaxed by pumping through a jammed filter unit. I have the older version of the Bronco '86 this unit has seperate fuel pumps one in the tank, and one near the engine. Some service shops will let you rent or borrow a fuel pressure gauge you should check for sure your self at the fuel rail on the engine. You should detect approximately 30-35 Lbs./In of pressure on a working system. There is a test for the regulator that you can use that is to run the engine (wi. gauge) then remove the vacuum line and read the gauge. The gauge should read 5 to 10 Lbs./In higher in a working system.
P.S I would stay away from many so-called injector cleaners to if you have a 5.0 Ltr. engine. Several of them are harmful; particularly some that promise extreme results. Many simply clog the fuel filter causing the filter to deteriorate sending junk down to the injectors.