my 98 outback has a driveability problem, but only when cold. This morn I got in it, started it & it just sat there & wanted to shut off. I tried to back it up but it just sat there, and the engine stuttered.  After a few minutes, I was able to get it to move, and then drove the 1/4 mile to the bottom of my street, then tried to up a hill. It sat at the bottom of the hill & for about one minute would not take revs at all.  Then, finally, it acted like it was shot from a cannon, and then ran normally for 12 miles to my mechanic's shop. He put his code machine on it & it said engine was misfiring on 3 of the 4 cylinders (it's the 2.5).  He told me to drive it 30 miles & bring it back. I did, he checked it & this time no codes at all, and the check engine light was off..  My son usually drives it & he said that after it warmed up, it ran good, but his $6 code checker still said one cylinder was misfiring.  HELP!!

Check/ test coil, wires and spark plugs. Check out injectors and plugs there. Likely something may be cracked or have bad connection that swells with heat to "cure" itself. It's different animal, but, I chased a random misfire problem on my Civic for a while that was poor connection of plugs on the injectors. Just a little tidbit to think about. Any other signs of head gasket problems on this car?

suspect MAF

how old are the plug wires? Is it worse on humid/wet mornings?

Random miss-fires are always difficult to track down. I recently had the same problem with my 99 OBW. It has the same engine as yours. I suspected a fuel problem, with maybe some bad gas with water in it. So, when I filled up with gas, I put a gallon of E-85 ethanol (gasohol) in to absorb any moisture, then filled the rest of the tank with unleaded. That helped some. Later, I changed the fuel filter, and that helped a lot. I also swapped in a new fuel tank filler neck, as I knew that mine had rust holes in it. That seemed to help some too. With poor fuel tank pressurization, the motor won't run right. Out of doing all of that, my 99 is running good again with no cold motor bucking, or hesitation.