Hello everyone, I just picked up a used 04 CLK 500 with 73k miles. I purchased the car from CHASE Repo auction. The car was parked for 3 weeks with out starting it.

After I started the carfor the first time, there was a very loud rattling noise coming from under the car, sounded like a loss muffler pipe or a loss heat shield.After driving the car about a 100ft or so, the Check ENgine light started flashing and it stayed on, but I was 200 miles away from home and there was no repair shops opened around that area. I had to drive it home or I was going to freeze to death.lol
The engine was misfiring like crazy, shaking, knocking,but if I restarted the car the engine ran fine?
After driving the car 160 miles, the exhaust rattling when away, and the engine was running like new? Ireally like to knowhow did my engine fix it self? haha...
I have been driving the car around for a day and there's nothing wrong with it, no check engine lights, no engine noise. I just want to know if this happened to anyone else and how I can provent it from coming back. Thanks for your time everyone!!