[KiDGiB]

I would start by removing that bracket on the intake manifold which holds the N249 and the N112. There's a lot of vacuum lines in that area you're spraying, so it could be the ones under the intake manifold too.

I replaced all my vacuum lines because the factory stuff gets brittle and cracks over time.

The other option is to do a smoke test (Might need a shop to do this).

 

[KiDGiB]

If you remove that bracket on the front of the intake manifold (Should be 2 bolts), you can get more room to reach under the intake manifold.

Picture for reference.