Mercury cougar '99 blinking lights....WHY???

I'm not really sure if they are dimming or blinking??? if they are dimming you have a parasitic draw. if they are blinking it sounds like you have a pats issue (Pive anti Theft) If the problem started after (They) touched it then they probably did not get something tight or used the wrong amperage alternator I also know that there is a few safety recalls regarding that year of cougar If it was me I would take it to a reputable ford dealer and have then verify that the recall for the alternator harness has been checked verified and updated.gl2u. P.S. I know you've heard the story before but I highly reccomend using a ford OE alternator not aftermarket.