Yeah, lately that's all I've been looking at (RPM's) It started bouncing at 500 and 300 right before it died this morning. The last 2 times it happen seemed to be shortly after starting up in the morning. The last time my wife took it to the store (about 3 mi away) and it died in the parking lot while she was waiting for a car to pull out of a spot. I'm certain there was no more than 1/2 tank of gas that time and this morning I have less the 1/4.
As for surges, yes, If I accelerate to like 40mph and then let off the gas, when it gets down to 1000rpms it'll surge to 1500 then quickly back down. There are other times when I'm 40-50mph and let off the gas and it doesn't slow down, it just hangs there for a while..
2006 4.7 Limited QD II, Stock