Q: Bad clunking sound when I turn the wheel on 1990 Audi 80

Doesnt matter if the engine is cold or 200 degrees my idle in park is roughly 700rpm and feathering the gas peddle when putting it into gear seems to have no effect. Already replaced the idle air control valve even tried changing the TPS though I think the new one is bad as it idles at 1500rpm and the engine still stalls when putting into drive/reverse. Thus far no check engine light.

We have had to replace the transfer case and now the mechanic said he has to take apart the differential to diagnose the source of the clunking sound. He says its likely to be the front differential. The car has numerous issues and has had a lot of repair work done. Any help as I have already spent over 4K on repairs alone. Right now she is parked as the clunking/ knocking noise is incredibly loud and always in the front of the car. The door for the boot is not working either , it was before a repair was performed but now it does not open at all.

I get a loose feeling clunk when going over bumps and potholes, I have high pitched whine on turn. Thick sludge is present on driveline/ujoint side of diff housing. Previous owner replaced broken trans with rebuilt one from wreaking yard before I purchased it. It shifts smooth but now diff sounds like axle on right is loose and sloppy and wheel is following suit as well can hear clunk at diff housing as well. No axle seal leaks at the wheel bearings can be found by my inspection. What should I do? Have done similar repair on my Toy 4Runner but only replaced bearings and seals with inspection of diff showed low fluid and no metal shavings present in drained fluid.