1989 Mazda 4wd

I have this vehicle with 166,000 miles. It runs great. The only problem I have is when it drops below 32 degrees it is very hard to start. It takes at least 10 minutes of pumping the gas peddle and then it will finally start. I have changed, the fuel pump, fuel filter, new battery, and tried fuel dry, thinking maybe water in the system. I have also changed the fuel sensor. This is a 2.6 liter efi motor. Any ideas?