Car does not start and will shut off going down road no power like key is off on 1999 Cadillac Seville STS

seems to becoming more frequent take key out and turn back on if gauges light back up car usually starts may have to repeat several times to start car but not always no check engine light on

Asked by for the 1999 Cadillac Seville STS
A scan test may reveal the problem.
Thanks I'll give it a try