Welcome to the forum, Ed. I've moved your post in here to keep it all tidy.
With those codes the most likely suspect is the EGR detent motor worn. Replacement is the only option, then install an electronic EGR controller. Search "SPV".
The 3 letter word search inability comes with the forum software that we use. You can get around it by using a wildcard 'egr*', or by searching two words 'egr P0403'. You can also enclose the words in quotation marks if it's part of a phrase you're looking for, "egr block".
ML is the first of the "new shape", 2007-2009. Came with 3.2 4M41 (detuned Pajero engine), 3.5 V6 6G74, detuned 4D56T (in 4x2) and a 4 cylinder petrol as well. That was rationalised in the MN (long tray, 2009-2015) with only the 4D56T high performance engine and a 4 cylinder petrol for 4x2. The new model, this year, is the MQ.
I think that the 3.2 has been available in Europe, but only in limited areas and special models. It is still sold in some markets like South America.
A catch can collects oil vapour that builds up in the rocker cover and is recirculated back into the intake system. This, combined with the soot that is fed into the intake by the EGR causes blockage of the inlet manifolds.
There you go, the sum total of Triton knowledge in one post.