I know it sounds weird, but when I changed out my intake I started getting the same problem. This is because the cable to the transmission runs over the top of the stock intake (at least it does on my 98 gtp), and messing with it was apparently enough to make the car think that park isnt really park sometimes. Everything still works, but the key gets stuck now and then. To get it out I just pop the hood and wiggle the cable. Eventually I will have the time to adjust it, but for now this is good enough. So if the normal stuff isnt taking care of it, try wiggling the cable to the tranny.