Furnace blows heat for maybe 1-2 min off for 30 sec and back on for 1 min or 2 and off for 30 sec... I took off wall thermistat connected both wire together and still on for 2 min and off for 30 sec again and again
Help what I might check next to diagnos... thanks Jerry

How old is your furnace? Is it new enough to have a circuit board and if so does the LED on the board blink any certain amount of times.