Furnace comes on cycles when it get to the flame lighting it lights and goes off after 10 secs... its not the flame sensor I changed it

If you changed the flame sensor and that did not fix the problem there is one other thing I know of that it might be, only if you have changed the thermostat or wworked on it lately.

There is a heat anticipator built into the thermostat and if it is not set right it causes heat in the thermostat itself. The heat satisfies the thermostat and it cuts off, the thermostat cools and it comes back on.

Now this is not the problem unless your heater is cycling on and off. Not if it just comes on and stays for ten seconds and then go off add does not come on again.

No the furnace cycles meaning the induced motor comes on then the ingnitor then then gas vavle open for about ten sec then shuts off and it does this 3 times then shuts down until u cycle the power

What model is the furnace?