engine does not reduce speed when I apply the brake. I think it may be a throttle sensor but not sure

I am basing it on the fact that the RPMs continue without slowing when I put the brake on. I almost hit the rear of the car in front of me because the motor continued at 40 MPH even when I put the brake on the stop. Actual driving experience.

Okay , needed to ask , I've had the other described scenario (the persons perception of the sound) more often than actual engine speed. Your best bet for proper diagnosis is to have a scan tool and monitor ALL data/sensor input/output for out-of-range readings , there are multiple throttle position and actuator motor sensors/controls(redundancy to help avoid the scenario you describe). Check for intermittent vacuum leak , ST/LT fuel trim may give a hint.