1988 Bronco II Problems?

I have a 1988 5-speed Bronco II and lately it has been running really rough. When I try to accelerate, it starts to bog out until I press harder on the pedal. A few seconds later it will kick in and make the whole truck jump. When I shift it into neutral the RPMs jump around and I have to press the gas to keep it from stalling out. On the freeway I cant keep a steady speed. Ill loose speed even if I'm pressing the pedal to the floor. It will correct its self in a few seconds and then do it all over again. I'm pretty sure its a fuel problem but I'm not sure. I always make sure to put good gas in it and not let it sit and build up moisture. I even ran Sea Foam in it. PLEASE HELP!