boost problem 08 gti TSI

I can't seem to find what's wrong with my car,
the only code I'm throwing is p0042.
My car sometimes has boost and sometimes doesn't.
When it doesn't it feels like I'm going from 1st gear to 5th gear in terms of power.
but I can left off the gas and push it a couple times and sometimes it will start to gain boost again and have full power.
I've replaced the DV, plugs, checked coils, checked MAF, when accelerating it sometimes sounds like im letting off the gas every couple seconds..
What would cause the car to have boost sometimes, but not other times?
I checked some of the hoses on top for any looseness but no luck..
I know it is probably a vacuum leak, but are there things I can do without having to make my own smoke test thing?

Have you found out what it is having the same problem

If you've checked literally everything, your best bet is to have the system smoke tested.

Das Gespenst said:

If you've checked literally everything, your best bet is to have the system smoke tested.

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I sprayed some carb cleaner around the engine with it started and the idle didn't change, i'll probably just have to do the smoke test like you mentioned.. I don't know what else it could be that's causing it except a vacuum leak, if that doesn't work I could start replacing injectors, fuel pump, filter, and clean the valves..