Some time ago my truck's performace dropped dramatically, acceleration was (even more) horrible, and there was a lot of black some out of the tailpipe when accelerating. Fuel economy was down too (7-7.5 km/l vs 8.3 km/l) Air filter was new and injector tips were replaced not long ago, so there was only one more subject, the EGR.

I blocked the vacuum hose that activates the EGR, drove a couple of kilometers, acceleration was good, and no more black smoke. Then unblocked the hose again... black smoke and poor acceleration were back! So good bye EGR and black smoke, and welcome better fuel economy and acceleration.