Warm starting

I've been telling people for years ,as I fixed their cars, I'm not a mechanic. And this one's got me stumped.

My '77 280Z starts great when it's cold, and it is getting cold here in Idaho,but last summer it would tend to flood, but only in the warmer parts of the day.Mornings were fine. Once started it runs strong. I have replaced both the distributor and coil,due to neccessity,I need to replace the radiator and water pump as the flow is not great and rad. is beat up(fixed a few leaks).Could this be the thermotime sw. or temp. sensor or cold start valve? Don't know where to start.

Thanx BRIAN