Limp Mode; HELP!!

i know there is lots of threads out there that explains you how to deal with limp mode but it seems like i tried everything and it still happens to me . I have a 2002 Golf tdi (alh) motor/turbo has only 50000km (rebuilt) and i keep having on issues with over boost / limp mode. i just changed the n75 valve and all vacuum lines. car sounds much better and accelerates much better too. However right after changing the lines and the n75 i went on the highway, was in 4th and passed 3000rpm and boom limp mode. i don't get it. i saw that my vacuum line from the vacuum pump to the brake booster was finished will be changing that soon but would that cause limp mode ? I also have a injector seal leaking i don't think that would cause it would it ? Turbo is basicly can't really believe that the acurator would be jamming. Is there anything else that could be causing this ? thanks

If the vac hose going to the booster is bad it can cause issues, and it doesn't sound like you checked the actuator, if it has a leaking diaphragm and won't hold vacuum then that can be the cause also. Change the large vac hose going to the booster and see what that does ( if it's leaking pretty bad you should have a somewhat hard to push brake pedal ). You also need to get a vacuum gun to test the actuator.