ok so my car has been acting up lately. 98 apr chip with a HFC.

The car bogs under heavy boost in every gear except 1st. I get studdering but will eventually get boost pressure to 18psi. I have had two codes TB closed open circuit and cat below threshold. I changed the fuel filter and only get the cat code now. I recently done the following:

cleaned the maf with sensor cleaner (not original 2nd maf)
new fuel filter
new fuel pressure regulator
cleaned the throttle body with brake cleaner
vag com TB adaptation
new rear 02 sensor (front one is not original got a used second one)
removed the waste gate hose off the n75 valve ( no difference)
I unplugged the maf got no boost but no studdering
checked the injectors they are all ticking and plugs are good and dry
I have about 50,000 km on my TT DV valve (i checked the suction with my finger still holds)

I am stumped and have read every post I can find. Need some help. PLEASE!

Thanks

 

How about checking for boost leaks?

 

I did a boost leak and the plastic cap i plugged the intake with blew right off! Held about 20 psi.

 

its possible you have a plugged cat. have you been able to check that out at all?

 

Its a brand new HFC cat. The car was doing it before the install just not as much it seems to be getting worse. As a normal everyday driver the car runs good. Its just when you want to get up and go and step on the pedal the turbo spools and then blahhh blahh a deep spuddering sound. Any other ideas you want me to try?

thanks