[fj40z]

So on the way home today I was stopped at a light when I glanced down at my oil pressure and noticed it was maxed out, needle all the way to the top. While I was stopped at the light I cut the truck off and the needle never dropped, luckily I was literally less than a 1/4 mile from my house. As I pulled into the driveway I put it in park got out and checked under the hood. I took off the oil filler cap and the engine idled way down,almost dying just for a second then went back to normal. I checked the gauge and it had went down a little. I let the truck cool down then checked the oil, it was about a quart low. I pulled the PCV (which was replaced this past winter) and it rattles so Im assuming it is OK. So I started it back up and drove it around for about 25 minutes and everything seems to be normal. Any idea what would cause this? Im clueless.