Well for some things you just have to be there. I have never looked into a manifold that wasn't wet but if you have raw gas accumulating there in any sort of quantity, what we have been talking about is irrelevent.
Clean up the mess and check to see if it returns. Unbolt the fuel distributor and lift it while bypassing the fuel pump relay to maintain system pressure and see if it drips from the plunger. If you have a leak you must address it.
Bosch Master, ASE Master, L1
33 years MB technician