Car intermittently won't idle down. at times runs 65 mph without
foot on gas pedal.

I have had the transmission checked (nothing wrong); disconnected the Cruise control, the only code display is PO446 Evap Control system which has been showing for 2 years. We replaced every sensor, took the Evap canister down, even replaced gas cap, nothing cured it. so I just drove it with engine light on. What is the problem?