Sure looks like it's missing/sputtering in the video to me. Maybe the ones who claim it isn't didn't watch the video clip? You can even see it puffing and sputtering from the white smoke blowing out the EGR pipe.

Don't underestimate the impact that worn valves/guides/seats can have on performance. A compression test may tell you something, a leakdown test would tell you more.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)