02 ford tarus

Car will not start when it is cold. If the temp is above 50 degrees it starts every time, but if it dips below 50 and the car sits for more than a few hours it will not start. I have to switch the key on and off 8 - 10 times to build the fuel pressure back up then it will start and run just fine. I have replaced the fuel pump, fuel filter and the fuel regulator/fuel rail sensor. What do I try next?

Please help!