2000 silverado 4.8 v8 runs bad when it is cold out side.

bad need of a tuneup? like new spark plugs, ?
172 , is 02 rich/ lean warning. this one is low oxy for rich.
this code can just be a victim. for sure , with misfire.
means 02 sensor stuck at rich,
what is water temp in engine coolant, at failure? less than 150F?
could be lots of things.
leaking injectors, bad fuel.
injector sticking> causing misfire.
id use a scan tool and watch all sensor when it fails.
too high fuel pressure.
misfires cold, but only luke warm cold starts not fully cold.

just one DTC, no P0300 or 30x misfire codes, not even P0300 pendings?

long shot guess, but a dam good one is your coil is bad. I'm 99.9 percent sure. Or coil wire bad

cold idle control sensor bad

Fuel Pressure Regulator !

Maybe battery or starter is going or positive cable to the starter is going bad.

check that your speedo cable is not close to exhaust and getting too hot causing cable to seize up

Could be the fast idle sensor check to see that the vacume line is hooked up properly.

Have your battery tested. It might have a bad cell causing it to not have enough "COLD" amps of cranking power.

CHECK THE COLD START ENRICHMENT VALVE AND OR THE IDLE CONTROL VALVE. I AM ASSUMING THAT YOUR VEHICLE IS FUEL INJECTED. ONE OF THOSE HAVE GONE BAD.

hi a bad water pump will not let the engine run normal unless it is frozen up. it sounds like your coolant temp sensor has gon bad.that will cause rough cold starts and work fine after warmed up