So i have been having a problem the last 2 months that has made me really mad.
I have yet to find anyone with the same problem.
What happens is when i start my car and let it warm up it runs great at an idle of around 1000 RPMs.
Then i take it out and for the first 5-10 minutes it will boost great and run like a champ.
But after about 10 minutes of steady driving it will only let my get to 5 pounds boost. And when i try to go over 5 pounds it looses all power.
Like it seems like the boost will just totally cut out.
Then after about 25 minutes i have absolutely ZERO boost.
So i have to just crawl up to speed or else the car will not go.

The weird thing is when i let it cool down for 10 minutes then drive it again it seems to get better.

I'm guessing it could be a seal somewhere or gasket that is getting too hot and causing a leak, but where would it be that it leaks all boost that quick? (INSTANTLY)

I have done a cold engine and hot engine boost leak test and fixed a few bad hoses but it still does this.

the only thing i notice when we hot test it is there is a high pitch whistle coming from the front of the engine but i can not pinpoint it.

also i replaced the spark plugs and it did nothing. (alot of people said that would be the problem)

the car is a mod free 1990 talon tsi

any help would be highly appreciated!