My Tempstar DC90 furnace will not relight after shutting off. Inside temp raises furnace shuts off. But when temp drops the furnace will not relight but the blower/fan will start up. I have shut off thermostat and furnace and restarted.It will light and run until temp set point. Board was replaced a couple months ago. I have been told it could be gas valve. Any suggestions?

True it can be a gsa valve going bad but that's only a geuss. Have the burners and flame sensor been cleaned? Was the gas pressure checked? I know it sounds like a lot of question but it's a place to start.