Will it start & run OK, does it stop after it gets hot then will restart & run again when it cools untill it warms up then stops again,it yes it can be a bad coil,I had this problem on a leaf blower.sometimes just testing for spark won't help you out it may still have spark but the electronics inside the coil that controls spark timing goes bad you could still have spark but it's out of time so the engine still won't run if you suspect this problem change the coil,bad coils can also make them hard to start.good luck