What I would do:

- make sure the wastegate actuator rod is attached to the wastegate flap lever.

- check the turbo impeller. You should be able to spin it with your fingers. There should be minimal radial play and absolutely no perceptible axial play.

- replace fuel filters.

- blow through the overboost solenoid. Air should move freely through the solenoid.

- blow into the manifold boost signal fitting. Air should move freely through the fitting.

- route a line directly from the manifold fitting to the ALDA and go for a spin.

- remove the ALDA and go for a spin.

- remove the plug on the #1 exhaust runner. If this helps performance even slightly, the oxidation catalyst is gunked up. Or is the trap still in place?

- open the ARV and check if the plunger is deformed or dislodged. This alone can't account for 30 second 0-60 times.

Sixto
87 300D