Oldsmobile 98 won't start when cold

I have a 1988 Oldsmobile Ninety Eight that won’t start when cold. Starts and runs fine any other time.

You need to elaborate on “won’t start” - that describes an awful lot of things. Specify exactly what happens when you turn the key.

When it is very cold outside the engine turns over, it trys to start, sounds like it starts to fire but won’t start and run. When it is probably 40 degrees plus and sunny it will start. We are in Colorado so even when it is cold it is dry most of the time, so don’t think it is a moisture problem. I can hear fuel pump running when key is turned on. Any ideas? Let me know if you need more info. I also replaced the spark plugs two days ago.

This seems to be a fuel problem. The fuel pressure may be too high. Check the fuel pressure after changing the fuel filter. The fuel/air mixture may be too rich. Check the ohms, or voltage, of the coolant temperature sensor. The idle air control valve (iacv) may not be bypassing enough air. Use throttle body cleaner in the iacv air passages, and in the throttle body bore, and on the throttle plate.