Car quits when it wants on 1992 Cadillac Seville STS

Well i use to drive my caidllac untill it start cutting off on me it use to take about a good 40 mins before the car would just shut dwn, and it will start right back up now it shuts downs after like 10 mins of idle and wont restart till like a half hour later.Can some one plz show me where to start looking Mechanic these days are charging to much

Asked by for the 1992 Cadillac Seville STS
i had this problem on my 2000 sts end up being ignition switch dealer wanted like $500 i did it myself for around $30.00 worked fine ever since