Hyundai Repair: 2001 elantra misfire after rain, high humidity, engine heat

Question
When my car sits in the rain for a couple of hours it will barely run giving me multiple miss-fires. I replaced plugs and wires and it stll happens, funny thing is, when I park in the garage then drive in the rain there is no problem, this only occurs when the car sits in the rain.

Answer
It's possible you have a problem with the ignition coil.  High humidity encourages unwanted high voltage arcing.  

In many cases, humidity in a garage is lower than outside, so parking there may reduce the issue.  I suspect the reason it doesn't occur when driving is that the engine heat makes it impossible for water to condense in the area.

You might also check your diagnostic trouble codes.  If the engine is actually misfiring, I'd expect something to be stored in the ECM and the check engine lamp to be on.