Well, first you need to tell us more about your fuel delivery system. Since you have a '73 and you mention the cold start something or other, I am assuming that it is the FI d-jet system.

What was mentioned to you was the cold start injector which is actually the 5th injector of your fuel system. It blasts extra fuel into your intake manifold for an effect I am sure you can guess. The injector could be plugged up in which case you could easily scrub the tip with a brush of some sort after soaking in gas or carb cleaner for a while. Pull it out when the car is cold, stick it in a jar and try the engine (fire extinguisher for all fuel work). If you have help you can watch the spray pattern. Should look healthy and misty.

Also check the temp sensor. There are two of these. One switches the injector on: I am pretty sure that it is the one that is stuck into the radiator (measuring coolant temperature). You can check the resistance with a multitester. It should read one resistance when cold, then it will change when warm (see your Haynes Manual). If this is shot, you will need a new one. Call the junkyards listed in my parts source, etc. pages.

This should be your answer for your troubles. It could also be any number of other things with that system. You need to get a manual so that you can trouble shoot the system. D-jet is a serious pain, but with patience I think you can iron out the bugs.

Good Luck, -jarrod

Parts Source, Etc.