Motor problems

i have a 1988 toyota 4runner and im haveing tubble with the motor it starts and idles ok but when i step on the gas it gose to a high rpm then dropes back down but i will be holding the gas pedle to the floor lots of back pressure to when i took the head off there was antafreez in pistons so im trying a new headgasket but is there anything else that could be wrong i got a new tps and a mass air flow sencer cus thats what the check eng litte kept popping up with just trying to figure out what could be wrong so i can fix it