I used a 9 volt battery, alligator clips, a hose, fuel, and compressed air to check/clean injectors.

Unfortunately, it was all the same stuff I was looking for with a random misfire on a 2.0 Neon. Sorry, O.P. : I did everything you did and after trying everything imaginable wound up taking it to a shop: burnt valve. Although I checked the PCV, I think the PCV was the problem all along. The intake had traces of oil in it. This is the first engine I ever had with a burnt valve, maybe someone can clear up what causes it?