Cant help you with your first question, but here is some info about your 300e taken from the cars section of this site:
The M103 3.0 liter inline 6 engine in the 1986-1992 300E's displaced 2962cc's or 180.8 cubic inches. While in SOHC 2 valve per cylinder trim it made 177 horsepower @ 5700rpm and 188 lb-ft of torque @4400rpm.

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1992 190E 2.3
150,000 Miles