take your AFM off and clean it with electrical contact cleaner. you may need to replace the pod filter entirely. You may even need to replace the AFM if it got damaged by the water.

disconnect your coils and remove spark plugs. clean the contacts with water dispersant and contact cleaner.

With the spark plugs out and coils disconnected. Crank the engine over a few times.

If you sucked up a fair bit of water, you'll need to remove TMIC or FMIC cores/pipes and make sure they dont have any more water pooled up in them.

put spark plugs/AFM/intercooler and everything else back in place and cross your fingers you didn't hydraulic lock your engine previously and bend rods.

Start it up.

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RS Liberty - Because WRX's are only good for parts...