If your car is equipped with an aftermarket cruise control, then it is possible that something did not work right and the cruise caused a problem. Otherwise, as has already been stated, only a mechanical failure in the throttle linkage that causes the throttle plate to be jammed open will cause acceleration. No malfunction of the electronics or injectors can cause the problem. The engine must have both fuel and air to run - if you overload it with fuel and do not also add the air by opening the throttle plate, then the engine just dies from over rich mixture. On your car, the fuel is controlled by the air mass meter, so if a throttle plate jams open, then the fuel system will provide the appropriate amount of air. If the problem is a hose coming loose that admits air AFTER the throttle plate, the air mass meter will not see the extra air and the engine will lean out and again, no power.

I have seen a problem on the 200 series turbos where the throttle cam that operates the idle microswitch can jam against the microswitch lever resulting in WOT jam - and yes, at speed the brakes are likely to fade and will not stop the car (has happened). Of course, judicious application of the ignition key witch ot the off position immediately solves the problem. Leave the car in gear and you will get enough engine revs to keep power steering, and the brakes should give you up to 5 full pedal applications before you run out of vacuum in the reservoir (assuming that your brake system is in good condition (many aren't! - ensure that the check valve is working!). Also - the tranny cannot cause the problem - purely mechanical linkage and down shift cable cannot jam throttle even if the cable sticks. Further, there is a spring on the throttle plate shaft itself, and another on the throttle spools - both would have to fail to cause the throttle plate to fail to return on that car and the failure would be obvious on an inspection after the fact.

Often the problem (barring a mechanical failure in the throttle assy itself) is that the driver catches the throttle pedal with the side of the foot when the brake is pressed - harder application of the brake gives harder application of the throttle and most drivers will not at that point take their foot off the pedals, but simply stand on them harder.

Personally, if this happened to one of my cars, I would do a very careful inspection of all the linkages while someone operated the foot pedal and then remove the throttle body for further inspection. I would disconnect each component to be sure that each link was operating properly - throttle plate properly centered in the bore, inspect bore for evidence of FOD (foreign object damage) etc.