If you have a voltmeter, set it to 24 volts. Put one probe on each of the gas valve wires, it does not matter which probe is on which wire. Run the furnace again, when the ignitor glows see if you are showing 24 volts on your meter. It sound like this furnace either has a Honeywell gas valve or it has an ignition control problem. If you are showing 24 volts at your meter, you will need to replace gas valve. If you replace the gas valve my reccomendation is a Robertshaw 720-079. Let me know if you need more help.