I parked my ’99 ML320 (125k miles) at my office a few days ago like I do every morning. At the end of the day, when I was going to leave, it wouldn’t start. The engine turned over like a champ (it has a new battery), but never sounded like it even wanted to catch. I left it there overnight and tried it again the next day with the same result: a healthy sounded turn over, but no starting or even coughing. So, I left it there one more night tried it a couple of days ago and it started right up like nothing had even happened. So, I drove it for a couple of days and last night I parked it in my driveway after I got home from work, came out a few hours later and it won’t start again. I am really confused about what it could be. The only other problem I have with it is a clogged EGR valve that causes a little shake when idling. The new EGR valve is coming in the next couple of days and I’ll replace it this week, but I don’t think that is the cause, because I have been driving the car for a few months since the EGR started acting up.