I noticed the other day that when I was revving the engine in park that the backlight for the display on the instrument cluster would start to flash when rpm's hit approx. 4k. Didn't think much of it. Then today I was on the freeway, stepped on the throttle to pass somebody and as the rpm's approached 4k again, entire instrument cluster shut down along with stereo. Everything restarted immediately on it's own but it was a little scary @ 70mph in traffic.

I'm thinking that the voltage regulator could be going bad?

I haven't done any testing yet but have a few questions.

1. Is the voltage regulator built into the alternator?
2. Could an over-voltage condition cause the symptoms described?
3. Has anybody else experienced similar symptoms?

P.S. It's an '04 F150 5.4 4x4 SuperCrew XLT

 

Sounds like the brushes in the alternator. If the commutator isn't grooved out you can replace the brushes, pretty easy job. If it has a groove cut into it then it's time for a new alternator.

That's where I'd start.