Thanks for your reply. With almost all the parts checked and replaced.... Now I am looking at the waste-gate actuator. This part is located in a hard to reach location. Any owner here have checked and replaced this item while the engine is still in the car before?
The only place I found is this part available from AVR, they have two version available. One is standard, the second one is with for higher boost pressure. I think I will get the standard waste gate actuator instead of the higher boost version.