Why does a 95 Camry hard to start in cold Temp?

We have a 93 CAMRY 4 Cyl Auto Trans and over 200K miles. One day it overheated due to a stuck thermostat and damaged radiator. After replacing both the check engine light came on and it was VERY HARD TO START WHEN COLD. Once it starts and warms up the problem goes away.

It turned out to be a fried CST (COOLANT TEMP SENSOR). Got it from AZ for $25.00 and used a 19mm wrench to replace it. It is located on the upper hose inlet into the engine block. Top right with the green plug.

MoMek