1988 Toyota Camry Keeps Stalling

need help with my car, every time i start it up and rev the engine or drive and step on the gas the pedal goes to the floor and the car only goes 30mph and then stalls, if i step on the gas lightly i can move but not that fast. i repleaced the air flow sensor and the transsmisson and engine are good any thoughts, please i need help.
thanks :banghead: