I have a 97 850 with almost 100k on the clock. While driving over bumps, small and large, i can hear a knocking noise from the engine area. I have replaced the upper strut bearings, thinking that they were worn out or loose. The noise still persists. The engine moves quite a bit while grabbing it on the motor mounts, though I've read that this is normal. Which if any of the motor mounts wears out around 100k? I will be checking the ball joints tomorrow to see if they are worn. I do get a little bit of vibration at speed above 65mph too. Hopefully this is something I can fix....soon.

Sounds like your swaybar end link. Cheap and easy diy job 1/2 job.

You can check which motor mount it is. The top motor mount is the one on top of the motor. If the insert is cracked or torn then replace it. Cheap and and diy.
The right motor mount you can pull the pass wheel off and and peel back the wheel well cover. You can see the mount. There should be a rubber insert. If it broken or cracked. replace it. Not really a diy job.
Theres another mount and most expensive out of the 3. I dont think they wear out often. Its usually the other two. You should probably replace both at the same time especially since you have as much play in your engine. When the right mount is worn it tends to break the top mount as well.

Thank you! You've given me another place to look, the swaybar end link. I will check them out and also the mounts more closely.

try grabbing the swaybar end link and if theres play or a snapping feeling then its shot. Dont go by physical appearance. Mine looked brand new when I replaced it. I just replaced the one side and vola.. no more annoying clunks.

Took a close look at the area, including the swaybar linkage. The sway bar is tight all around. When I place my hand directly on top of the shock tower I can feel the clunk sound as I push the car down. I've put in Bilstein shocks a few years ago along with lowering springs. I wonder if it could the spring making noise as it contacts the top of the strut or the bottom side? The right side is louder or more prevelant than the left side when doing this. Both sides do the same. I checked the tightness of the nut on top of each tower, along with the star nut under the rubber top cushion.
Could the shock be bad internally? I do not get an after bounce.
As for the motor mounts, the front mount, next to the crank shaft looks fine. I will replace the top motor mount though as it is cracked in several places.
Thanks so far to those who've answer my plea for help and advice.

could be the strut bushing or strut mount. (I cant remember the exact name of it)
But I would still try to replace the end link first. Its cheap.
Also when I pushed my car down it was doing exactly what yours was. no bounce but a clunk. It was doing it whether you pushed down the left or right side of the car. I didnt think it was my end link either. I replaced it because hoping it was the problem (which it was) and thankfully i didnt have to pull the strut apart (which would have been the next step)

I guess a quick way for me to check is to disconnect the swaybar end links from the strut towers and see if the noise persists. thanks, i'll respond with my findings tomorrow.

Checked it out by removing the link on the right side. When I place my hand on top of the strut, and push down I can still feel the slight thunk as before. I wonder now if it design flaw with the upper strut bearings. I recall that the sound was gone when I replaced them less than a year ago. Unless I somehow managed to install them incorrectly on the strut assem.... Could the harshness of aftermarket springs and Bilstein shocks cause the strut bearings to wear out quicker? Sorry if I've asked this already, my thoughts are rambling at this point.