The odor you report from under the hood is an indication you have fuel leaking out somewhere. This can lead to air leaking in when the engine is turned off. This can lead to injector like symptons as air will interfere with the fuel delivery.
My 1998 E300D TurboDiesel has had a running problem with fuel line leaks. I finally had the dealer take intake manifold off (he found a gasket leak that needed to be fixed under my Starmark warranty) and replace all the lines, that, like everything else that needs attention, is located under intake manifold. I still get a whiff of Diesel now and then, but the car starts like it does not know about the ambient temperature. Let it glow and it starts immediately. Good luck, Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)