RX8Club.com - Not exactly sure waht to make of this

Hi all, long time since i posted in thie forum, hope i didn't miss much hehe :)

So, here is my condition as of late.
Car starts fine when cold, no problems at all, runs fine and happy, no hesitation or anything of that sort. I have noticed a strange sound comming from the intake area (stock intake) at around 4k RPM when I leave it at that rev range, almost sounds like an airy metalic sound, not sure if anyone else had this. Similar sound comes up near the redline.

Now, when the car gets up to operating temp, my idle gets rough, idle RPM fluctuates quite a bit, when it hits the lower 800 rev range the car shakes a bit (though motor mounts seems fine) and some times, the car dies altogether and refuses to start again until some time later if I let it sit for a while. I haven't had any error codes, no missfires or loss of power, which I would assume would point to engine failure. Bad fuel pump mayme, overheating and seasing?

In either case, any feedback is apreciated.
Sone info on the car:

2004 6-spd Manual (Hi-Power)
25(ish)k miles on a rebuild street ported engine.
Greddy cat-back and running cat-less
Car was serviced 1000 miles ago so new air filter and spark plugs (problem existed before service too).
Racing beat spark wires installed a couple of years ago (on purchace of car).
Due to street ported engine, I'm runing a custom map. I had the tuner check if the map was the problem, but we did all sorts of logs and they don't show anything out of the ordinary.

Not sure what other info I can provide, but ask and I will try to provide!
And thanks all in advance ;)