Certainly not sure of your available tools but take a common plug and connect the plug wire to it, then ground it to the engine - turn the engine over and see if you have a blue/white spark, go to the next one. If that checks out, I would check compression in those cylinders.
And a tip for others. You can make your own plug tester with a sparkplug and electric wire clamp (like on the end of a 12v timing light). Remove any insulation on the wire clamp and then weld one handle side to the side of the spark plug. Open the gap on the plug to about .040-.045. Now you can plug it into the end of the spark plug wire and clamp it to a ground point to test for spark.