GTR Running bad when warmed up

[SDTCloutier]

This problem just came recently. I was on highway everything was fine than , I heard this weird sound coming from my exhaust ( sound of a fat guy having Diarrhea ) and than the boost was unstable and the car was loosing power.
I pulled the car on the side of the road and listened to the car on idle. I turned off the engine let it cooldown for 5 min and the problem was gone.
It happened a couple of time.
Now when i go for a ride after 5 minute when the engine is warmed, it keep doing it non stop(sound like stuck exhaust)
so i tought it was exhaust problem ( probably cat ).
I removed it,it was stock,melt,cooked (I tought it was the problem) so i empty it and put it back.
still doing it.
I was thinking maybe a piping problem,missfire ,turbo who are getting old,bad compression.....

Well, im looking for some help and advice ( sorry for my english ,still working on it :P)
Ill try to post a video of the problem too

any help or knowledge would be apreciate ( so i can have an idea where to look to find a solution)

Thx .

[Black BNR32]

strange...try removing the cat and take a test drive.

[SDTCloutier]

I found what's going on. One spark plug is dead.