Goodman GMP075-3 furnace won't fire up the burners. Replaced the flame sensor, validated all fans are working correctly, checked HSI igniter, cycles with the rest of the system and get's 'yellow/orange' hot, system shuts down after 3 failed cycles to light. Resistance on the igniter when cold for at least 5 min measures at 100ohms (service manual says should be 40-75). I can hear the pressure sensor;s faint click in start-up as well as gas valve click after igniter lights up. I am unable to smell any gas before or after the cycling. HThe water heater is on the same gas line (it gets gas just fine). I also and checked @ the trap of the main gas line right before it goes in the furnace. I(opened slightly) and could smell gas, then re-closed/sealed it. I verified that the chassis of the furnace is electrically grounded and it reads @ 120V with correct polarity. Also verified that gas valve is receiving 24V upon powering of HSI igniter. Assuming at this point there is nothing left to do other than replace the gas valve and hope that it solves the issue. Any other suggestions I could do before paying for this expense?

Also, the lock-out failure code was x1 red flash repeating every 4-5 seconds. Also, system was working until about 3-4 days ago. I did a full cycle of the system, and it started running for at least 10 minutes (was off by morning). Tried it again the next day, and would only stay on for about 2min tops. Now burners completely fail to fire.