i had trouble like this with my 85xlx before. it seems that coils will kind of 'wear out' with the heat of the engine, vibration and age. i would be riding along and it would cut out like yours and then would be fine. after a while it will cut out permanantly. then it is time to get a new coil.
the coil is mounted atop the front cylinder, right? it gets a lot of heat from the engine and heat from the electrical current running through it. add in the vibration that all sportsters have and you can guess that any component has a rough life on a bike.
i have used the stock harley coil, the screamin' eagle and accel coils and it will happen to all of them in time. i like the screamin' eagle ones the best of the three mentioned though.

 

It is right on top of the front cylinder. I don't see how it would already be going out. I've only put 5000 miles since I put it on.

 

What kind of coil is it? Does it provide the proper resistance?(ohm rating)
If it is a high compression problem, then a compression release would be in order.
Usually a compression problem would not relate back to the coil. It usually destroys the starter.

 

I have the twin tec coil. Its the correct ohm rating.

 

How long would your coils last?

 

H I have a 2004 Roadking Classic. Up in Tahoe this past week and my bike started to cut out and stumble at low speed, especially in traffic where I had to slow down. Thinking it may be the coil, colds 24&25 are set. No other codes set. OHM checked coil cold and was in specs. Ran hair dryer on it and the 0.5 to 0.7 went up to 2.1 on the front and the rear. Next is the fuel system. I stll think it ts my coil.
Don luckyace

 

I'm having similar problems with my bike. Did you ever figure out if it was the coil? I'm still trying to trouble shoot and any leads would be helpful.

I know the manual says that it could also be a temperature sensitive cam position sensor. I haven't had the time to test it yet....