if you have a hole venting/sucking to atmosphere in your intake you MUST block it
here's how the list works
air filter
afm
intake
turbo
intercooler
throttle body
intake manifold
combustion
now after the air filter you have the afm (the air METER device) it measures how much air is coming into your engine so it can squirt in the right amount of fuel for the air that you sucked in
BUT
you have an extra hole in your intake AFTER your air metering device which when your turbo sucks in air now it is not only sucking air from the filter it is now sucking in unmetered air
too much air = not enough fuel
the ecu is only putting in enough fuel to support the air it metered not the air you sucked in afterward
so to sum it all up
answer = detonation = pitting in the pistons = (depending on boost) meltdown of internal engine parts = new engine
not a fun exercise
silicon on those sorts of parts is not recommended.... you can get a new o-ring from anywhere, you just take them yours and ask for a thicker one but same diameter
so are you still having misfiring problems or are they gone?