hydro therm boiler flame keep turning off

The burner flame keep turn off after couple mins not the pilot light. To turn the flame back on, I need to switch the power on and off and sometime the flame stay lit , most other time i need to do it couple times for it to stay lit. My friend said to change the thermostat and remove the air from the boiler so I did both of that, but the trouble still not resolve. There are 3 zones for my boiler with 3 thermostats. The blue top is for basement, the middle is for my bedroom but both of the thermostats always shut. The bottom is the main zone with the new thermostat I just install to heat the whole house. If anyone can give some tips to what I can do to resolve this issue,

Thank you