Usually this problem is cause by old spark plug wires, but you say yours are new?

I believe your diagnosis is correct - if you smell fuel, you probably have an ignition problem, where the high humidity reduces the dielectric constant of the air gap between two conductors, resulting in spark leakage.

It must be related to a high voltage section of the circuit, so you're looking at anything from the coil to the tips of the plugs. Kind of hard to think of what might be the culprit, though, if all that stuff is new...
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Speed Racer, '83 240 R, '74 164 E, '93 940 OL1 (Manchester, CT)