I keep having to stroke the power on my furnace to get it to come on. It does not always light on first try. Sometimes I have to do this several times. I have replaced the filters. I have clean the flame sensor with sand paper. I have cleaned the furnace. It will run fine for 2-4 cycles then right back where I started.

Is the code on the control board-- flame proving failure? If you count the blinks on the control board it will give you the reason for lock out