Engine shuts off when the accelerator pedal is pressed to the floor

The truck will start, and idle, but when I give it gas, it hesitates at first revs up. If I put the pedal to the floor and hold it, it will shut off. If I put the pedal to the floor and let it off, it chokes a little bit, then goes back to idle. Just replaced the mass airflow sensor. I've replaced the knock sensor and harness, the O2 sensor, throttle positioning sensor (but nothing changed, so I returned it), distributor, and igniter. When I was replacing the mass airflow sensor, I noticed a wired connector that was not connected to anything. I cannot find what it goes to anywhere. By the way, it's a 1993 Toyota 4wd truck.