1987 760 Turbo, automatic trans:

Yesterday, while trying to merge into traffic on the freeway I noticed an acceleration problem with my car. When trying to accelerate fast (when using the turbo) the turbo would "whir" (much LOUDER than ever before) and it would whir and whir and whir and not shift gears. I had to let up on the gas, as the car was NOT ACCELERATING AT ALL and i was afraid to burn up the engine. It was only over a long time and a great distance and without using the turbo that i finally got up to speed with the traffic. While trying to accelerate with the turbo engaged i also noticed small amounts of BLACK SMOKE in addition to the very loud WHIRRING (it has always whirred a little and it has always worked, but not now). Also, while driving on surface streets where i don't have to use the turbo, the car shifts gears fine. I am not low in ATF or oil. I DO have loose bushings at my gear selector, though i don't think this has anything to do with the problem.
if anyone has any ideas as to the cause of this problem (i guess you'd call it a long long long hestitation to shift when using the turbo) let me know. also if you need me to explain more, let me know and i'll write back.
thank you so much
trina