Electrical mystery

Only about three times has the truck done this but it is a 1999 Chevy Tahoe and usually at idle speed and in gear the truck will lose power stumble and die and usually be tough to start after that. The funny thing is I though it would be something of a fuel issue but one of the times that it happened the interior lights flashed the truck died and when I went to start the truck again it was like the thing was dead. Nothing not even the orange gear selector was lit on the dash when I had the key on power.
A few magical seconds later power was returned and the truck started. I noticed that the clock on the radio was reset so there was a disconnect of power. I checked the battery and the battery connections and they were tight and corrosion free. It has not happened since and I am not TOO worried about it because the thing usually starts after it dies. Any suggestions to where I should concentrate my time on diagnosing the problem???? Thanks everyone

Bad connection between the battery and the ignition switch. Check them all.

If your '99 Tahoe is an "old body" style I may be able to help with a more detailed trouble-shooting system than the previous response. Let us know.

thanks, I will look at everything then. how do i trace the cables back to the ignition switch thats under the dash inside right????

Check the battery cables for loose or corrosion. Follow the power wires to the fuse block(usually red). From the fuse block through the dash and to the ignition switch. A wiring diagram will help(Haynes).

yes the '99 is the old-old body style