I'm not familiar with diesels, but...
I would just replace the O² sensors - they're cheap, fairly easy to get to, and can't hurt to put new ones on.
MAF sensor, also would just replace it for the same reasons. Someone else here can chime in on what it really is/ called/ does... I forgot where that conversation went.
Soot? No idea. But I get the feeling you may want to replace the air filter, too.
That's all I got.
I would just replace the O² sensors - they're cheap, fairly easy to get to, and can't hurt to put new ones on.
MAF sensor, also would just replace it for the same reasons. Someone else here can chime in on what it really is/ called/ does... I forgot where that conversation went.
Soot? No idea. But I get the feeling you may want to replace the air filter, too.
That's all I got.