I recently went through the same problem of a leaking bottom intake plate. Went through two gaskets with no success. finally got it by scrubbing both matting surfaces with steel wool, to a shiny finish. Cleaning it up with carb cleaner then using AISIN FIPG.
Sounds like an idea. Did you torque those bolts? I just snugged them up. I'll have to pick up some AISIN FIPG
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