I too find it odd that it would go like that. After reading the initial symptoms, it might also be wise to check the rear brakes. I had a problem with the emergency brake pads rubbing on the rotor after putting new rotors on for awhile.

Have you done any brake work on the rear just prior this starting??

Just a thought if it isn't the differential.

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89 190E
2.6L
Arctic white
Grey leather
Sunroof
Pirelli P400 rubber
Smoked corners