plymouth voyager starts when it wants it truns over but no fire

I guess I have to assume you have the 3.3L engine? Have you checked for 12 volts to the coil during cranking when it doesn't start?

yes

when its cold it dont start

Have you checked for 12 volts to the coil during cranking when it doesn't start?

Have you checked for diagnostic fault codes? Do you hear the fuel pump run for one second after turning on the ignition switch?