Furnace Short Cycling
I would start by trying to find a service manual for your furnace, and see if it has a troubleshooting flow chart.  

I am thinking either:


Something is not functioning correctly, and the control board is shutting it down to prevent damage
A sensor is reading incorrectly
The control board is having issues and not applying logic correctly.


If the control board is detecting something wrong, it might throw an error code.  Previous systems I've used had an LED on the board that would blink out the error code.

You might be able to check the output of the various sensors by back probing the connectors.  You can do your 8 hour reset to determine the 'good' values, then test it when it is short cycling to see if these are different enough to cause the control board to think something is wrong.

Look over the control board for signs of damage - blown capacitors, burn marks.