Mercury Repair Questions? Ask a Mechanic for Answers ASAP
Does this only happen at the first start of the day after the car sits all night?
It's a misfire. Possibly a coil or plug wire. I would take it back and have it checked. Sometimes you will have this issue when it's damp out, then as the engine runs and dries out the misfire stops. They will likely spray some water on the ignition system and check it for arcing. This is what causes the misfire, once the coil or plug wires are replaced the issue will be resolved. The flashing check engine light is usually the giveaway to an ignition issue.