I've been suspicious of the IP, since I've tried pretty much everything else. Bench tested IPs are not inexpensive, I'm sure, so I'm trying to not overlook other, more simple tests/fixes.

Brandon (OR) looked at it last year - wondered at first how we could drive it at all - tried some things, then scratched his head, and mentioned he put a re-calibrated IP on his, and he couldn't be happier...

Oh, and I should include: 82 300TD 345,000 miles

Haven't really checked anything to do with the turbo myself. I will say, though, she's "all ahead slow" way before the turbo should have anything to do with it...

So, where does one get a re-calibrated use IP, and is this probably going to be the way to go (once we've ruled out everything else)?

Someone also mentioned removing the ALDA altogether - just to see if it's the culprit - does doing so make any sense?

Call Lee = in my signature.

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

Have you checked you fuel pressure?? This will determine whether or not you have some sort of restriction and the condtion of your fuel system. This should be added to your list of preventive maintenance ie. fuel filters, valve adjustment, ect!!!