Look in your rear-view mirror!

Are you blowing black smoke when it does that?

Could be you have an intake leak, caused by a split hose somewhere after the turbocharger. In other words the "charge" air is leaking out before it reaches the throttle body. Your AMM is reading so much intake air, while your throttle position switch is telling the ECU "I need a lot of fuel right now, guys!"

Trouble is, too little air is mixing with that fuel dump, hence, unburned fuel, incomplete combustion.

In my '89 740ft, is is usually the curved hose from the IAC valve up to the intake manifold which is split. I also needed to replace the short hose from the intercooler to the intake pipe.

Best way to find these leaks is to undo the turbo outlet side of the hose leading into the intercooler. insert a plastic plumbing cap (1.5 inches diameter) into which you have drilled a hole large enough to take the rubber nipple of your shop air blow gun. You need only 10-15 psi.

the leak will become evident. Either a hose, coupling loose, or a leaking intercooler (least likely)