Sounds like a problem in the torque converter. My dads
F-150 had a similar problem. It wouldnt go when you released the brake and only then it would go when you got on the gas and then it would spin the tires. Not exactly sure what happened, but that seems to be similar.

92 Rodeo, 3.1 TB crank, custom bumpstop spacers, DOR shackles, Flipped ball joints, D44 Rear, 4.56s and new magnaflow cat and dynomax ultraflow muffler Since been replaced by a 2 door Explorer on 31's shackles, cranked torsion bars and full exhaust