OP - I listened to your video. What one hears on a youtube vid and what they hear in person are quite often 2 different things, but all in all, the car does not sound all that bad.

If you google "M103 fuel smell" and read all that's out there you'll find more than one post where the problem "seemed" to self-heal. I don't believe in voo-doo, but before you start throwing a lot of $$$ at this, I would simply ensure you have a good fuel supply(filter(pump(s), spark plugs, air filter. etc(the easy to do basics) and eye-ball the EHA and injectors for leaks.

A lot of these older MB cars that are picked up used have been sitting around for a good while with little or no use. The best thing you can do sometimes is fill the tank with fresh fuel and drive the car as much as possible.

Years ago there was an MB forum known as the Ritter-Easley List. A tech on that forum would occasionally advocate what he called an "Italian Tuneup". Ensure you oil is clean and full; then take the car out and push it, watching for radar of course and finding a suitable place to do this. I'm not advocating triple digit speeds, just a good bit of spirited driving.

Over a period of time you may find the vehicle performing better with your only expense being gasoline and your time.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"