Great starting became hard starting.

Picked up a half inch carb spacer to help with carb boil. Will pull carb off tonight and go through. I think I have enough parts lay in around to pretty much rebuild. I noticed some brown crap in filter. Everything on fuel system is new so I am thinking could of boiled off the fuel?
New tank and lines too? The 'brown stuff' would not be from fresh fuel boiling off. Older 'gunk' is more likley, as MO sez.

BTW, consider a full heat shield, not just a spacer. The spacer does not prevent heat from radiating up from the intake and into the bowls.
Like this:
Holley 108-51: Insulating Carb Gasket Heat Shield Fits Holley Model 4150&#0153 and Model 4160&#0153 Square Flange Carbs | JEGS