Stick a screwdriver in the end of the spark plug wire and hold it away from a ground somewhere and see if it sparks that way. If its spark there you know the coils and wires are good so the plugs would be the problem.

If know spark there pull the wire off the coils and spin it over. The coil should ark to the negative terminal, or a ground somewhere on the coil so that way you can rule out the coils. You can also touch it and see it is shocks you. lol doesnt hurt that bad but you can definitely feel it. I wouldnt recommend this method though. Ive done it a few times though.

If nothing from the coils it could be the coils, pick up, wiring, Lots of things.