mazda will not start

[steve kite]

mazda mx5 mk2 1.6 2000 36,000 miles 1.slight engine miss fire but ran on 4 cylinders when reved 2. engine failed to start, removed plugs and replaced with new. engine started fine 3.engine fired for 4 days 4.engine failed to start no spark detected 5.car left for 3 days engine started and didnt miss a beat for 4 days 6.taken for diagnostic check. no fault found. also no error codes detected. 7.2 days later miss fire on start up