I have a Bryant Plus 90 Furnace about 20 years old. Don't run every often. We have secondary heat. I turn the thermostat up in the morning works good for
Several cycles then it want come on any more until I go turn the power switch off and on.
Comes on works fine for a few more cycles then want come on.

Try cleaning the flame senser. When it gets dirty, the furnace will operate speratically.