FWIW, my car had similar problems. It felt like the turbo effect was MIA until about 3,000 rpm. I replaced all the fuel filters, tank screen, boost related hoses, and even the cat converter. Although a new cat helped, the car was still not the way it was when I bought it.

After reading some of gsxr's posts on ALDA's I decided to remove mine and pressure test it. It would not hold any pressure. I got a similar ALDA off of an '82 turbodiesel (yes, it has the same part number as the one from my '87) and it held pressure. I swapped ALDA's and added an extra spacer and my car is finally running the way it was when I bought it.

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold