Dunkirk Q90 boiler gas valve cycles open/closed, locks out if happens too many times in succession

I think the boiler is trying to restart when the temperature is still good, so it shuts back off within a second of the gas valve opening. How can I make it wait till it cools a bit before it attempts to re-ignite? I keep hearing the gas valve open then immediately close. Most of the time this doesn't cause a problem, but some times it cycles as described too many times and the computer locks it out, resulting in waking up to a cold house. I checked the condensation drain and it seems to be fine.