The threads on those bolts are Thru holes.
You can try put the silicone in the link below,
on the threads of the 4 bolts.
Pull them out one at a time and clean and coat them with silicone.
If that don't work then it's intake gasket time.
Link:
https://www.amazon.com/Permatex-8187...0002UEOPA?th=1