My heat comes on this is hot air furnace runs foa a while then it shuts off, and in about 30 seconds it starts back up and goes through the same cycle

My hot air furnace comes on then it shuts off and in about 30 seconds it is starting up again

Thermostat heat anticipator not adjusted properly.

Dirty air filter

Closed registers

Blocked return air

I doubt it is a flame sensor problem but if your no name no model number furnace has one clean it. If it is a gas furnace that is.