Idle problem

[redsand]

I have a year one 350 crate with a quick fuel 750 carb with electrical choke which I had to remove to fit into the vortech supercharger cabinet. The supercharger is currently not hooked up. Took it on the maiden voyage and all was well until I put the car back into park. In park the car progressively increased rpm and would not go back down by tapping on the gas? When putting it back into drive the idle dropped and it was fine. As soon as I put it back into park same thing happoned again?

Any ideas why this would be increasing in rpm while in park?