Blows 3 amp fuse. After fuse blows fan comes on. Ignitor works prior to fuse blowing but no gas. One resistor on board appears to have black mark.

This is not a common, easy problem I can just paste in an old answer for. Which blower, the main one that circulates the air, or a small one for the combustion air? Normally the air handler wouldn't come on until the furnace warms up. There could be a short in the gas valve wiring, but I would be surprised if it blew a 3 amp fuse. Check it. Check anything else that feeds off the fuse that blows.