Hello, currently my '98 subaru OBS 2.2L non turbo is having trouble starting.
The issue started on a rainy day when I forgot to put the baffles back underneath the air vent on the hood that is directly over the MAF sensor. Parts of the engine bay got wet including the intake area.
When I tried to start it that day, it threw a code and it was undriveable because it idles very hard and will stall shortly after cranking. It seems to be running too rich at idle and running lean on acceleration. It also idles high at over 1000RPM.
I think this is a MAF sensor problem because A. The code (P0103 Mass Air Flow MAF Circuit High) directly points to a MAF issue and B. I forgot to close the rain guards in the hood vents over the MAF sensor and some water got into my engine bay.

Today I tried cleaning it with MAF sensor cleaner and shooting the connection terminals with compressed air, but the cleaner only made it run worse. Surprisingly, the sensor didn't like being cleaned with the MAF cleaner becuase when I start it, it stalls out almost immediately after cranking the engine instead of after 30 - 60 seconds. It also starts to shake a little violently and then die out to 0 rpm and stall.
I tried starting it like this a couple times but I decided maybe I could blow something up if I kept letting it shake so hard.

I tried resetting the code a couple times by disconnecting the battery and it still has the same problem and gives the same code. I am about to buy a new MAF sensor on eBay for about $35, but I don't want to buy something and have it still not work. Can anyone please help me out? Could my MAF sensor still be good, but maybe my a wire is being shorted by moisture somewhere? The air vent is almost directly above the MAF sensor so maybe it got shorted out by the water when I tried to start it. Someone please lead me to the right direction.

UPDATE: Today I changed the spark plugs and finally got a chance to work on it and visually inspect things again today. I saw the horribly corroded and gunked up spark plugs and was hoping this was causing a misfire of some sort and causing my engine to stall -- unfortunately that was not the case.

I tried running it without the MAF sensor and it idles rough, spits out a ton of excess gasoline from the tailpipe but runs more stable than with the MAF sensor on. When the MAF sensor is plugged in, sometimes it would not even respond to the accelerator petal and reduce the RPMs to 0 regardless. Both idle very rough and shake the engine quite a bit before it died out. I did this a number of times, hopefully not ruining anything else.

Also, I noticed a slightly faint buzzing noise coming from the idle air control connector when I turn the car off and Not sure if this is normal or not but just something I observed. I'm going to take apart my intake assembly and put it back together so I can closely inspect all the parts, vacuum hoses and throttle body.

 

You could try drying the MAF (gently) with a hair dryer ..

 

Unplug the maf and see does it improve.

 

I've had it outside of the car and sitting inside my house in window sill to dry it off that way. Left it sitting out for a couple weeks, no improvement.

Joe, as I stated towards the end of my post, when unplugged it runs better and stable, although when revved spews a ton of raw gasoline out of the tail pipe. I'm thinking it probably is the MAF sensor, but I'm not sure. I hooked it up to a live data on my OBD2 and it was getting some readings of air being inputted, but I'm not sure they were correct because that was the first time I ever looked at the data for the airflow.
Thank you for the replies.

 

If it runs better with maf unplugged its your maf sorry didn't read/need to read all your first post it's a common problem.

 

UPDATE:
So it was indeed the MAF sensor gone bad. Maybe water got inside of it and fried the circuit board. Idk. I bought a refurbished MAF on ebay for $30, installed it today and cleared the codes.

Took it to the gas station and back no problem. It idles lower than before too and steadily at 300-400. Not sure why, but my guess is maybe the computer is still in learning mode. It hasn't stalled like before so I think it's A-OK. Thanks for the input everyone.

Was super hesitant on buying this new sensor since people online say they rarely go bad, but in my case it was the MAF sensor gone bad.