Rather than a hose, use a spray bottle and mix as much salt as will dissolve into it. pure water is actually an insulator, it's the 'stuff' in it that makes it conductive. Unless your intake system is set up weird (like a giant horn sticking through the bumper) any car wash sprayer shouldn't have a line of sight or enough power/volume to choke the truck out. also won't cause problems 20 mins later.

the AFM (vane type air flow meter... not technically a mass air flow sensor/MAF) electronics are sealed so unless the seals are bad you oughta be able to dunk it without problem (not that I'd try).

I would take a good look at the ignition system. there should be a rubber o-ring under the edge of the cap and a vent with a turnaround to keep water from getting in. My truck had trouble when I got it that whenever there was condensing moisture around, it'd get a really bad miss over about 10% load for the first few minutes till it warmed up enough to evaporate the moisture. I couldn't figure it out and replaced both the AFM and TPS. then one day I was fiddling with the timing with the engine running, palmed the distributor and got a nice series of zaps. New cap, rotor, and wires and hasn't had a single miss since. I've hosed the engine down several times, even with a cone filter, and no trouble at all.

 

Ok, I finally replaced the distributor cap and rotor (thank god that it doesn't rain much around here) and my truck was purring like a kitten in the car wash today. I had finally popped the hood and drizzled some water on the distributor, and it was like flipping a switch to kill the engine.

Thank you for the input.