I have a 1998 Chevy Silverado with 111000 miles, recently the ABS light came on and the speedometer quite working, the engine also got weaker. I shut it down, for a couple minutes. When I restarted the light went off and all was back to normal. Then ...
Did you notice anything else stop working, like the radio, blower motor etc?
Grab a voltmeter and the next time this happens don't turn off the engine, but check to see the voltage on the fuses in the fuse block is. If lower than battery voltage, suspect a bad ignition switch.
It is related to ABS system, you need a high level scan tool with live data monitoring to see when the issue happens, what exactly triggers that.
Sounds like a lost vehicle speed signal. Check the wiring harness to your transmission.
