Stall and incorrect MPG calculation

Here we go. I have had this aurora for about 6 months. When I got it I immediatly tuned it up and it has been running great except for a few things. Sometime when coasting around 40 or so I can feel and see a surge in the RPMs. Not sure what that means. In addition my MPG calucation and fuel used calcualtion is off by a couple of gallons after driving through a tank of gas.

Sometime recently I have also noticed the RPM's also fluctuate at idle like it was going to stall but it doesn't. Well today it did and took a few seconds of cranking to get it going again but it ran fine.

No SES light.

Originally I was thinking fuel pressure regulator so I popped the hood and pulled the vacuum line while the car was running. Nothing. It seems fine. The car was fully warmed up and I left it like this for a couple of minutes. In general I do not have a hard time starting the car, if ever. So I don't thinkg its the FPR.

So back to the MPG calculation. If the calculation is off then it suggests that fuel is getting into the engine that the computer can't account for. And there are only two ways that I am aware of that this can happen. One is through a leaking FPR, the other is a leaky injector. So what do you guys think. How should I go about testing a leaking injector?

Thanks

Okay I just pulled the injectors and turned the key, no fuel out of any of them and rechecked the FPR, still nothing. No leaks I guess.