1985 Lincoln Continental IDLING

Engine Performance problem
1985 Lincoln Continental V8 Two Wheel Drive Automatic 67000M miles

when I start the car in morning it starts ok but when I start driving for a few minuite and begin to reduce speed to stop, the engine start acelerating and speeding up without touching accelerator so I have too apply brakes hard until it stops and then I put it in park and I can tell that idle speed is very high. It is a 5 liter efi engine. Let me know as soon as possible and if your solution works I will make a donation for sure. Thanks nick