Speed Control Springs problems of the 2000 Ford Expedition

Throttle feels like its sticking. The breaks feel like they get harder the longer you drive or use them. Its been extremely cold the last few weeks (air temp of -28f lows to -3f for highs). You let off the break from a stop sign or stop light and it will suddenly accerlerate by itself. Seems to happen anytime after 40mph, even if you slow back down to 10-15mph it will accelerate back up on its own, up to as fast as 65mph!) I need to downshift and ride brakes (which are hard as a rock!!!) to keep it from excelling though town and to try to keep the rpms at bay. When coming to a stop and turning its hard to steer and it makes jumpy/jerky movements forward when brakes are applied. When vehicle comes to a stop the rpms skyrocket until you shut down the engine. If you havn't given it enough time before you start it again, the engine and rpms soar up again. Things we've tried with no luck are, disengaging the cruise control, replacing the spring under hood where the throttle cable is. Thought maybe it was stretched and not depressing fully to alow deceleration. After that we replaced the throttle body itself. Again, no luck on test drive. You can hear a click/ping in the pedal and see it come up once truck is in park, give it time. Pedal seems to be partially depressed and there is play. Have tried to stick foot under the pedal to try and get it to disenge. Worked the first few times that's also why thought it was the spring. No longer works to do that. Can seem to hear a difference either in motor or trany, acting as if it's working harder when it seems to take control of itself. Started happening 12-24-17. Been to the shop many times with no answers as to why this is happening. It's very scary and dangerous! after reading about all the others this is happened to its hard to imagine that there hasn't been a recall or at the very least an answer yet!.