190e 2.6 fuel (non) economy

[jbwabco]

i have a 1987 190e 2.6 a/t. now i'm still getting used to the workings of this thing and learning from this forum. with that being said my question is about my fuel economy has dropped to almost nothing, getting about 8 mpg. o2 sensor seems to be functional (just assuming because dash light doesn't come on), i've got a service cd and it shows an air intake temp sensor on the scoop. on my car the scoop is missing and a don't see a pigtail for where the sensor would plug into. btw i posted on parts forum for anyone that may have an air intake (from scoop to air cleaner box). but back to the point - where should i begin looking for issues. i have a good amount of hand tools and a dvom multimeter to test, but lack the "german knowledge" to diagnose. and now for something completely different, while under the hood i noticed the drivers side upper strut mount is broken, can it be replaced w/o having to compress spring? (can't find that on cd either) thanks guys!!