It just happened overnight.
The problem now is when the car is warmed up and idle dropped to about 1000 then the car behaves funny that the exhaust has black smoke coming out and sounds like "poo poo poo" not smooth with the car shakes slightly. I look at the boost gauge it apppears it has slight higher than usual. It used to be -0.5bar at idle but now it goes up and down around -0.4bar.
While driving the car behaves like normal just at idling it hehaves funny.
I have changed ignition coils, spark plugs, air flow meter, o2 sensor, fuel pump since i noticed the problem. I just reset the factory ECU too (reflashed ecu) last night and so far it seems a little bit improved that black smoke from exhaust looks like disappeared at idling but idle boost is the same up and down around -0.4bar (usually at -0.5bar) and still "pooo- pooo- pooo"

 

When mine started acting like that I blew the oil seal on my turbo. The bearing took a dump and ate the seal.

 

how do you test it to confirm it is where the problem is? apparently i borrowed a power fc with basic settings and the idling boost is fine and idles smoothly.