help. any ideas

Hi guys. Had my vrs rolling roaded today was scanedd before the runs no faults. We ran the car 4-5 times and then left the car sitting for about an hour. Went to leave and the car wasnt even making 5psi. Rescanned car and was coming up with n249 mechanical fault so we undone the bypass same problem. Replaced with the rolling road operators leon cupra same. We even tryied his maf and n75 same. Anyone any ideas what to look at or do next.