Just got back from a ski trip to Colorado and had some problems with the 1995 S-350 Diesel. I did all the cold weather stuff like fuel antigel and such but the morning after I got there, when I cranked the car up it started running rough at idle and smoking excessively. It would run a little better after it warmed up at highway speeds but as soon as I slowed down and let it idle it would run rough ( like a miss ) and smoke. I added some Power Service octane booster and cleaner and ran it for several tanks but the problem continued until I got back to a lower altitude. I am from Louisiana. My first guess is injectors. Has anybody else had a similiar problem? How do I test the injectors? Car is running great now I am back home but I know something is wrong and don't want it to happen again if I travel to a high altitude place. Car has 173,000 miles and never had an injector off of it.

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1995 S-350
370K + SOLD
1952 220B Cabriolet
39K kilometers + SOLD
1998 E300D
310K +
2012 E350 BlueTec
120K