There's a square aluminum canister on top of the injection pump.
It has a sealed adjustment cap on top...pry out the black plastic seal and loosen the nut....turn the screw out about one turn...lock the nut and test drive. Continue adjustment until best performance.

This adjustment controls the tip-in fueling of the pump. They are set lean from the factory...they get leaner over the years.

Also check to see if WOT is moving the i/p arm to the stop located between the engine and the pump.....try this with engine off !

You could see if the turbo boost control is not opening too soon.
On the drivers side inner fender is a electric vacuum valve that opens/closes boost pressure to the pump.....re-route the vac' lines to by-pass this switch for a test.


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