I would start with the easy stuff first.

Fuel filter change.
Valves adjusted?

If everything else checks out OK, I would turn the screw on the ALDA. My car had the same symptoms and I ended up turning the ALDA screw almost a full turn CCW. Now it runs like a beast.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R