1995 fat boy- harley davidson

This is going to be a problem that will need to be tracked down because there are several things that could cause this. It's going to be in the electrical system, and any one or combination of the following can cause this, Faulty switch, especially the ignition switch, bad wiring which could be a bad connection, loose ground, bare wire, or broken wire, These are the two cheapest, but the hardest to find. Now, it can also be a bad or malfunctioning ignition module, coil, voltage regulator, and magneto assembly. You will have to test each of these. I recommend that you start at the spark plug end and work your way back since most of this is in line and work in conjunction with each other. Keep in mind that this being an intermittent problem, it may be extremely hard to find.
I also have a 95 Softail, and recently had a similar intermittent problem, turned out that there was a hairline crack in the regulator, and the problem would only occur if the regulator was warm enough for the crack to open a bit. I also traced the wiring harness, found and replaced several wires that were in bad shape, thinned, stretched, corroded, etc... You will be amazed at how much wear the wiring harness will have on a 13 year old bike.
Don't let this discourage you. In my opinion, the mid to late 90's models are the best HD ever built, and the Evo is by far the best engine. With the newer bike you have to worry about things like, crank and cam sensors, ECM's, fuel injection, and all the other electronic BS. It's to the point that the average rider can't work on his/her own bike, which is getting away from the HD tradition. That's a great bike you have, keep it for a long time. I may buy a newer bike someday, I don't know, but I do know that I will always keep my 95. Good luck with this and be safe.