When passing the car continued to accelerate , had to stand on brake engine conntiued to race and was shut down, engine restarted with no appearent damage. but we are now totally unsure about driving the car again. also a few weeks prior the car suddenly lost power in city driving again restarted fine

I would think you need to find a service center that can scan your computer and find out what is not working correctly.

Hi Jackie , It doesn't have to have a code stored in the ECM memory for a problem too exist . need some more info from your if you would like some ideas as to the problem !
What engine does yours have ? 5.7L ? What type fuel system does it have - TBI - throttle body fuel injection ? I had vehicles at the Chevy dealer I worked at with this type fuel injection , where the engine raced really fast . Vacuum leaks , bad plug wires can cause this problem . The engine computer is compensating for more air entering the engine ! After fixing the problem it still was racing , you have to drive the vehicle an get the speed up over 35 MPH for the ECM to reset !

This sounds dangerous, this should be inspected by a dealer.

run fault codes and check for accelerator position sensor problem Check for MAP/MAF sensor faults.

Replace the air filter its clogged.

It sounds like your Idle Air Control Valve (IAC) is sticking.

Replace your IAC motor. This is the "idle air control"motor. This control the amount of air needed to keep the vehicles idle stable.

sounds like your carb is getting to much air some where check your hoses

When you passed the truck... I guess you couldn't tell if the pedal was stuck since you were focused on braking.

When you brake, your brakes will overcome the acceleration of the car causing it to slow down, but like you describe, the second you let go of your brake, your car accelerates again.

It would sound like either the throttle pedal (gas pedal), the throttle line (connects pedal to throttle assembly) or your throttle assembly (on the engine) may be sticking....

throttle position sensor. or idle control sensor