Hi, I'm a new member and thought I had already posted my question, but I can't seem to locate it. So, here I go again. Condensed version: Goodman Gas Furnace... 2years old. Blows cold air. Electronic ignition... ignites flame burners, but they turn off prematurely after about 2-3min. Then after a short period they re-ignite... this cycle seems to continue. Blower works fine, but air never warms. Changed the cycle in the Thermostat to a longer period... still no difference. Finally, thought to check air-filter... it was filthy. Had only operated the furnace for about a day with the dirty filty... had hot air in the morning and cold air when I returned from work. Any suggestions/comments are greatly appreciated. I'm in Houston and we just had a cold-front move in. Thanks. Cheers!

If the airflow problem has been corrected, check and see if the burner lights and stays lit for the whole heat cycle, if the burners are cycling on and off the main limit has gotten weak and needs replaced.