Pull the terminals and clean them with the wire brush tool for the job. Just because you ruled it out, don't be stubborn and not do the 5 min maintenance task.
I am at 160k with an issue like this but less frequent. Either my terminal is loosening or I have bad power wire to the starter. Once running my truck will not die.
After that you should look at all the grounds under the hood. The should look clean and the wire not brittle if they are these are weak points for current. Being in the land of winter salt I am willing to bet you have a corrosion issue with some wiring.
99 x-cab 4x4 4.0l auto
mods, cranked t-bars, silencer delete, k&n drop in, Rebuilt trans ,Trans Go stage 3 shift kit, 3200stall Fuddle Racing Torque Converter,
VANIR 63mm TB, Roush split rear exit exhuast, E-Fan, JBA Headers
Auto up/down both windows, OHC, EATC (soon to be modded)
03 Crown Victoria Police Interceptor