You said "2. Emptied fuel tank and cleaned fuel lines (some dirt uncovered);"
My guess is you have contamination in the injectors. Try using a double-dose of injector cleaner on less than a fuel tank of fuel. Also, I had success in bleeding the injector lines at the fuel distributor (danagerous if not extremely careful) but effective.
Does the car not have a lot of power and then all of a sudden it gets power around 4,000 RPM?
Keep us posted,
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)