Valet Mode -- Limiting speed
I'm trying to figure out a way, that once I put the vehicle into valet mode, the car would not be able to go over a predetermined speed. I have a Ford Explorer with cable actuated throttle. I was thinking that if somehow I could convert the mechanical throttle into electronic throttle control, then, putting the car into valet mode would intercept the throttle pedal's signal and only allow a maximun of ,say, 5% of WOT to limit the engine's speed. My thinking is that in normal mode: No throttle = 0% and WOT = 100% thereby reducing speed if only a 5% signal is the new maximum at WOT in valet mode. Of course I would make it so that if carputer failed I could manually reset mode via hidden switch.
If converting to ETC isn't practical, then is there a simpler way to do it?