1993 Diamante Wagon

6G72 SOHC (per bank)

runs fine cold and warming up, when hot(operating temp) the spark goes away, comes back after it cools off.

could be the coil or coil lead
or the dissy cap or module

usually just a broken coil. wet it down.

Yeah, that was it, wet the coil and it starts missing and almost dies. While we were test driving it the front seal on the trans went out also. Looks like another trade in junker.

There is a minimum voltage a battery has to put out all the way to the starter motor in order for it to be able to generate a spark, and there are conditions (bad alternator for example) that keep this voltage level below the needed threshhold.

Also I do know that when cars are hotter, the voltage levels are affected by that (i.e. voltage from your battery to starter motor). If your alternator isn't working well, your battery may be undercharged and thus not have enough voltage to cause a spark. This happened to me. I got it fixed by an auto sparky fitting a voltage relay to the car, but I probably could have just changed out the alternator with the same result, as the battery was fairly new.