I would replace the ignition module with another one. DLE 30 was my first gasser. When I set up the plane and test run the engine it shut off on me and would not restart until I turned the ignition off and then back on. Didn't think anything of it as this was my first one and thought I screwed something up. I ran a tank on the ground after that and had a wonderful maiden day of flying. Then a week later after a successful flight in the morning, I had a dead stick 5 minutes into my flight. I recovered the plane in the field and turned off all switches. When I got it back it fired right up. We looked it over and found nothing so Idecided to fly again and sure enough 5 minutes into the flight it deadsticked again. This time I tried to start it again out in the field and it would not start. I also noticed that when I looked at the digital tach I have under the canopy that there was no RPM being registered when flipping it over like I noticed before. All I did was turn off the ignition and back on again and it fired right up. got it back and drained the fuel to go home but wanted to fire it up to run it dry. This time it failed almost immediately and same thing as before, no rpm registering on the tach until I turned off the switch and turned back on. In the end DLEsent me a new ignition module under warranty and I have now put over 3 gallons of fuel with zero problems. Even though the issues are not exactly the same, they were both intermittent. Many of the ideas posted are valid but most don't cause intermittent problems like you are describing. Usually fuel system issues or air leaks are always there and do not come and go like you describe . A faulty ignition module/switch/battery/opto kill etc could most certainly cause an intermittent failure and ignition issues can very easily be mistaken for tuning/fuel issues. You could change the pickup as mentioned already but in my experience it is rare to see a hall effect sensor fail intermittently. usually they work or they don't unless there is a mounting problem. If you have the option to try another ignition I would do that first.