What is wrong now?
 

So about 2 weeks ago I'd be driving my car and for no apparent reason it would go real lean in Vacuum. In Boost it runs fine. The car also would idle at around 1300RPM. I thought maybe this was a vacuum leak around the injectors, cause when I put my 460's in, I forgot to put those little washers on the injectors and when I started the car it idled at like 3,000RPM. I swapped the seals off my stock injectors and then the car ran fine, but the seals felt hard like they were old. So since my car started to idle high again, I went to the Mazda dealer and bought new seals. Last night I went to swap them on there. The car was warm cause I just had it out all night. I pulled it into the garage and pulled the top of the intake off and heard a small hissing sound like there was some kind of pressure bleeding off. The sound was similar to when a tire has a nail hole in it. I then pulled the 3 bolts that hold the fuel rail down, and the rail blew itself off the injectors and all the pressure released.
What is the problem here? The first thing I thought of was that maybe my FPR is shot, but what do you pro's think?

Well if you didn't disconnect the fuel pump relay and let the car die, the fuel rail probably had 30-40psi of pressure in it still, so that sounds normal.

Surefire way to find vacuum leaks:

Get a can of Gumout/carb cleaner and spray it on all connections/joints/whatever including the injectors that could cause a vacuum leak. Make sure you let the car get warm so the idle settles down before doing this and spray a bit in the intake just so you know what it does (basically it revs up a little bit).

Chiming in to second the fuel pressure staying in the rail. I happen to have a gauge underhood (came with dual feed stuff I bought from Samnavy) and the fuel pressure remains around 40 long after the car's been shut off. Good luck!

Thanks for the 2nd opinion guys, that pressure staying in the rail makes sense to me. I'm gonna throw those injector seals in tomorrow and put the car back together, and hopefully it'll idle where it's supposed to, and my AFR's won't go crazy.
Thanks again.

So I got those seals back in there, brand new ones...started the car, and same thing. When I drive it down the street, the AFR's go all over the place in vacuum, but in boost they are smooth and solid. My vac / boost gauge reads the same it always did, and I even opened MT and compared the kPa gauge to my vac boost gauge (vacuum supply line t's off MS supply and goes to gauge.) The gauge and the MS are reading the same. If I listen while the car is idling, I hear what I think is a vacuum leak. This is when I put my ear on the passengers side front of the engine near where my BOV is located. I tried to disconnect vacuum lines, pinch some shut, you know, try to single out the problem. Still nothing. It almost sounds like the leak is coming from near the fuel rail, but I can't believe it would be injectors seals cause like I mentioned, I just swapped new ones in there. Perhaps there is a small vacuum line under the intake that can't be seen without dismantling it? This is driving me nuts!