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Just had the same situation on my 91 L98. It was leaking on the intake header and boiling off. I had to replace the intake header seal which was no a cheap fix
My '95 occasionally had antifreeze odor and I dreaded fixing the heater core. But the floor never got wet and the aroma didn't increase for a year or two.
Then one day at red line the 'flow control' (a flow restrictor in the feed line from the water pump to the heater core) broke and antifreeze shot all over the engine compartment - mostly on the passenger side. Of course the wife was with me and had to sit in the car while I walked for emergency plumbing parts.
The valve seemed redundant and fragile so I left it out. After researching what it's for (keep the pressure on the heater core down during high rev's), I went to the dealer and got a new one for under $20. No more occasional antifreeze aroma.
Check that 'flow control' for dampness. Mine split where one end appears to have a cap and nipple (the other end has only a nipple).
Good luck.
Feel the underside of the carpet on the passenger side at the fire wall. Mine was leaking but the carpet never got wet, it just ran down under the rubber backing of the carpet.
check your thermostat housing / intake manifold area for discoloring. had a similar problem, where barely at idle was barely bubbling. could smell it alot, but did not leak anything.