I have tried several things to try and alleviate this issue. The latest attempt was the fuel heat exchanger, aka fuel pre-heater. The fuel line leading from the top of the heat exchanger to the fuel prefilter was leaking heavily, so I just decided to throw a heat exchanger at it at the same time.
So, here was the starting point:
I removed the crossover pipe and intake manifold, the plastic valve cover cover, the set of black tubing that I'm not sure what it is, tranny and accelerator linkages of course and I drained the radiator. {heat exchanger gets into water jacket of head}.
Here you can see the old fuel line that was leaking BADLY at the top of the heat exchanger. It goes from top of heat exchanger to prefilter.
I removed the two fuel lines and then the heat exchanger. {I'm guessing the lower fuel line is the supply line from the fuel tank, so this lower fuel line connection seems like the logical place to hook up diesel purge setup. Found NO forum info on that though.}
Hmmm, inside of head looks extremely clean!!
There is a gasket between the heat exchanger and head, so I of course installed the heat exchanger with gasket and installed the new fuel line. {leak was caused by flattened out o-ring at bottom connection. These engines don't really need the whole fuel line but I imagine just the o-ring. These o-rings aren't in the EPC, but the Mercedes parts guys version has o-ring part numbers}
Put everything back together and there I was back at my starting point.
now is isn't cold right now, not even close, so I can't test to see if this fixed the problem. However, upon a very hard acceleration it was doing it's "cutting out" thing which often accompanies this problem, so I don't think my issue is fixed.
My guess, tired/worn injectors.
sigh.........
heat exchanger: 604 070 00 79 $75.65
gasket: 604 078 01 80 $03.14
fuel line lower oring: 601 997 04 45 $02.46