Any ideas's what would cause this???

Sounds a lot like blow by to me? Like compression was getting past. It would explain the excessive pressure in the crankcase and rough idle. Did it by any chance give you a big "chug" under hard detonation like there was a big miss? I don’t want to scare you, but you may have damaged a piston. They’re only hypereutectic in those things, you know? It may not be bad enough to puff any noticeable smoke out of the tailpipe, and it wouldn't overheat if it was damaged. Oil pressure would only be affected to any noticeable extent if there was bearing damage.

Pull out the spark plug and check out the electrode. If it's no longer there, then there's a good chance that it could have taken the piston with it.