sounds like an air leak to me m8

I have a similar problem with mine, however I was told by local scooby specialist to remove the intercooler and check the gasket on the back of it as this is a common problem with them.

The other thing to check is the maf itself, with the engine running, disconnect it, and see if the engine cuts out (mine does) which means the maf is working fine, but if yours doesn't cut then this might well be your problem.

HTH