2003 Mercury Sable Stalling

My wife's 2003 Mercury Sable is experiencing an intermittent problem. She'' be driving around, here's a "pop", dash lights come on. Sometimes the vehicle stalls, sometimes it doesn't. Mercury can't find the problem .
They say no codes are set. As time progresses, it appears this is more prevalent in rain or snow, but not necessarily driving through puddles.
Problem developed after Ford repaired an engine oil leak.