I took Power last Oct, and felt the same as you guys; I did well in the morning with plenty of time to check my references, and left for lunch confident on all but (IIRC) 3, but I had to outright guess on 10 of the PM questions. And who knows how many of the ones I *thought* I got that I actually screwed up... I was pessimistic, but after the 3 month wait, I found out I passed, and they actually reported my scaled score- 85%. So buck up guys, and good luck!!
And remember- the REAL stress is not sitting at the PE exam, it's when you finally get then envelope in the mail and start to open it. I wonder how many PEs collapse from heart attacks at their mailbox?