Is it noticeably running on 5 cylinders? Only at idle or accelerating/higher PRM's as well?

It takes a fair amount of compression leak to show up as a miss. SO much so that usually a 'shade' tree compression test can spot it.

Pull the wires on all three coils, then crank the motor around for a short bit. So you don't flood the motor with gas, just do it a few times round and round. And listen as the start labors over each compression. Whir, whir, whir, whir... LIsten for any spot int he cranking where it sort of sails on by a compression without slowing down (as much).

Easy, quick to do, no tools needed, and if you hear uneven cranking, then yes, you've got big problems and will need to do more diagnostic work. Leakdown tests are great because they tell you where the compression is going. Out the PCV system - bad piston/rings, maybe a HG. Out the cooling system, probably a bad HG. Out the intake or exhaust, something wrong with a valve.