I disagree with almost everything except a sticking EGR valve. That's rare for a complete no-start, but possible. I'm banking on the coolant temperature sensor (CTS). Reason being that the computer bases injector pulse width on the coolant temperature. If it won't fire in cold, but will when it's warm, logic tells you that the engine is simply stuck starting lean. The CTS is most likely stuck high. If it's never been replaced, I'd suggest doing so. I did on my '87 notch, and the car has started perfectly ever since. Before, I had a few problems starting when it was particularly cold. Very similar to what you're describing. Check your computer codes and see if the computer is reporting problems with it. However, it's also very likely that it WON'T because it will assume everything's OK if it's within certain parameters. All the computer knows about the coolant temp is what the sensor is interpreting.
BTW, the CTS is the large gray thing screwed into the metal heater pipes on the passenger side of the engine, right on top. I would NOT use any sealant or tape on it, they come pre-gooped at most parts stores. Good luck!
