I have a E220 Cdi (year 2000 model), I was getting loads of black smoke out of the exhaust on hard accelleration. I looked inside the EGR valve and it was completely full of black tar-like deposits, as I couldn't get the EGR valve off I cleaned it out using a toothbrush and spraying WD40 into it. This cured the smoke problem, but now the car intermittently goes into "limp" mode, ie lack of power, no kickdown and revs limited to 3000. The limp mode comes and goes, but when I unplug the MAF sensor, limp mode is definitely on. I can floor the throttle when parked and the revs do not go above 3000. When I plug the MAF sensor back in everthing is normal. Can anyone help??? Is this a faulty MAF sensor? The problem only arose after I cleaned out the EGR valve.