Down flow gas furnace is acting up. All burners not fully lighting regularly?

The hot surface igniter glows red, gas valve opens and ignites gas in one of three chambers. After about 10 seconds, sometimes the "flame" travels to the other two chambers like it is supposed to. Sometimes the flame does not travel to the other two chambers and the furnace recycles and tries again. The flame sensor is in the chamber farthest from the chamber with the hot surface igniter that lights up first. The furnace is in a new home that is about 3 years old. I have also noticed that I have 3 cylindrical sensors in the burner area that appear to have reset ons on the tops of them. I am guessing these are the flame "rollout" sensors. Does this sound like dirty burners or "crossovers"? Record cold temps are on their way and would really like to get the furnace operating correclty. Please help.