Toyota Camry

I have 1992 camry station that starts hard. It all started this past winter when the temp got down to 25 to 30 degrees the wouldn't start unless up put heat on the throttle body tube(hair dryer) and know its doing it all the time. After the frist start up it starts fine.I don't haft to put the heat on it in the summer to get to it to start.I have change the plugs, wirers, cap and rotor but I didn't change the little senor inside the cap, I also changed the fuel filter. It has four cylinder motor and has 317000 miles. And its an automatic.I asked a question awhile ago and made a small donation and never got an reply