1992 Cadillac Deville and the car seems to "lose all power" and surge at times when driving. When this happens she can pull of the road & sit there a few minutes & let it cool down and be on her way. This seems to happen only when it is hot out & her engine gets hot. This week it has happened over the past 3 or 4 days. Other times, it won't happen for a month or more.