Car's idle is messed up

[DSM BoosT]

when I first start the car it starts out at like 1200 then when the motor warms up after a min or 2 it settles down to 800 900, when I drive for a bit it still stays around 900 BUT as soon as I put it in park (automatic) then idle goes up to like 1500 or sometimes 2000 and it never comes down below 1500?????? help no idea it only happens in park and the beginning of start up.

 

[400hp93talon]

Have u checked all of your vaccum lines because when i threw my motor back together last week i forgot to put the line on the front left side of the intake just above the fuel rail and it wouldnt idle and did exactly what yours is doing but my car is a manual.

 

[DeadsEvolution1]

Check your vacuum lines and check for boost leaks