On cold starts my car's idle surged from 400-1200 RPMS and dies if I step on the gas quickly to past 3krpms and let off, even at idle. Could this be a PFC issue? I had the PFC tuned by XS for my mods not too long ago. When the car warms up it drives fine and the idle holds.

 

How cold? you can adjust the fuel value by engine temp on the power FC... also check your plugs, they may be getting old, weak spark on cold engine = bad idol when cold...