HELP>> Ruud silhoutte II not working

My furnace runs fine for a few days, then i either come home or wake up and the heat is out. I take the top panel off, simply touch any random wire and the unit kicks back on for a day or two. I have replaced the air filter which has now prolonged the lapse inbetween the occurrences. I have made sure all wires are tightly connected, i cleaned out the area where the flames shoot out. I don't know what else to due....PLEASE HELP!!!!!!!!!!!

I had an issue with the water pump (from the dehumidifier) failing and causing the heater to stop working. Once the pump was replaced everything worked again. I also had a problem with a Ruud where the blower had a lot of buildup and needed a serious cleaning. The pro's will have more suggestions.