I recently cleaned some vacuum lines on my 300sdl om603 turbo, most of them are ok except for the one connected to the nipple on the intake manifold which was plugged with oily stuff. I felt the increase in power after cleaning up that line.

Now that it seems like a different car. I'm not sure what the cruising RPM should be. At the moment, my engine revs at around 3200 at 60MPH on the highway. I can feel the engine breaking when I let off the pedal at this speed. Is this normal? or am I missing my 4th gear?

TIA