2002 Subaru Forester Engine missing at start up

first thing to do is to wait untill night and make sure it is dark outside no lights on and pop the hood, then block the wheels and then put the truck in 1st gear and run it slowly accelerating up to about 3000 rpms. do this with the brake on also of course.

have a friend standing under the hood looking for sparks to appear, kinda look like a light show, if that doesnt do it try it in second gear then try it in drive.

if you see excessive sparking from wires replace the wires, if you see them near the coils the coils may be bad.

you could also opt for a nice warm day and pop the hood and slowly mist each part of the engine untill it starts to run rough or stall out, if it does you have found the problem.