Adjust linkage to make sure you're reaching full stop on the IP, grease linkage balljoints as this will make accelerator feel much better
If you don't adjust the valves don't bother trying anything else. It should be the first thing on your list. You could try checking to see if the injection pump timing is correct. Might want to hook up a pressure guage to see how much boost you are getting at WOT. Adjust turbo wastegate if below spec. Other than that that's all I can think of.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)