Catalytic Converter Warning and Black Smoke

I am using the 2006 model Peugeot 206 HDI. I had an excessive black smoke problem for about 1 year in my vehicle. Some said turbo, some said injector. I used it this way. We recently cut and put sheet metal into the EGR valve. The smoke turned gray and when I opened the front hood, there was smoke. We canceled it again.

On the way to Ist-Muğla last week, the catalytic convector warning burned. Although it was extinguished when fuel was taken from Shell; On the way back from Bursa to 4th cycle from 4th gear, the car made a fatigue like shaking back and forth, drowning. I was able to come by shrinking the gear at high speed continuously. The next morning, the car drowned. I took it to a different master, connected it to the machine. EGR valve corrected alert, increased traction. He said you should change the EGR if he gives a warning within 1 week. The warning came on again. Do you think it is from EGR or will I clean the converter? There are buyers in the vehicle. I don't want to cost.