Rough runner

I have a '94 Ford Ranger pickup. It has only 62000 miles on as I ride my bike a lot. It has been a good runner until recently when one day I started it and the engine ran as rough as if one cylinder was missing. Out on the street it smoothies out a little but lacks power. Since it?s drivable I?m trying to troubleshoot it myself. It has the 2.3 L 4 cyl. Engine with distributorless ignition. I?m thinking that the probability is that the problem is not the ignition because of the relatively low mileage, the two ignition modules and two plugs per cylinder. Does this make sense? My guess is a clogged fuel injector. I put in a bottle of Gumout fuel injector cleaner and have driven it about 40 miles with no results. How long does it usually take injector cleaner to work? is it possible to use a scanner on it? i don't see anything about that in Chilton's. Any other ideas? Engineman