14 Maxxforce dt soot issue

Hi all, I have a 2014 international 4300 with the maxxforce DT engine that keeps building soot and causing random low power.
The engine on this truck was replaced in 2019 with a new engine. I would guess it has around 50k miles maybe a little more on the engine. About a year ago the EGR crossover seal on the intake side blew out. We replaced the seal and it blew out again shortly after. The then clamped the pipe (doesn't appear to be deformed) and it hasn't had an issue until now. The driver says when this happens he takes a rubber mallet and hits the cat and dog and it starts to have power again. The only code is the code for tc1 top. When we pulled the pipe off last year the cooler looked not plugged. Any ideas?

 

Just a note. When the issues started again I noticed the seal had slightly pushed back out and I tapped it back in.

 

Ok I will do that tomorrow. Problem here is unfortunately even the dealers don't know much in my area. I was fortunate enough to be able to talk to a service manager out in California and they gave me some good information as well. I'm hoping someone else has had a similar issue that could shed some insight