Aftermarket DOC/DPF

[mikkhh]

Provided that you live in a place where it is legal solving those problems for once and all would be the go to choice.

I highly reccomend to buy scan tool (inline-6 from china works fine OR genuine nexiq that costs many many times more) to read fault codes, reset derates and read programming by yourself.

If you already have scan tool you can pull the programming and send it to somebody who can take a look and maybe can sort things out.
https://rawze.com/forums/showthread.php?...5#pid72945

Instead of aftermarket DOC and DPF I would have old original ones baked clean.

Pull the egr cooler and wash it (or use compressed air to blow it clean). DPF doser valve may need replacing too since it has 750 000 miles on it.