Check voltage drop across the pressure switch when the heat is on and see if it drops out just before the burners do.
Does your furnace have a honeywell smart valve? Igniter plugged into the valve, hot surface pilot ignition?
If yes, post the number off the valve.
Does your furnace have a honeywell smart valve? Igniter plugged into the valve, hot surface pilot ignition?

If yes, post the number off the valve.