Your symptoms of temperature related failure are consistent with the failure mode of the cruise control on my ex-1990 560SEL.

JamesDean rebuilt the underdash unit, and that fixed the problem.

Not certain about the 95 diesel, since it retained some early features (the gas cars were updated), but the M104 cars have a completely different cruise system than the earlier cars ( M103 and OM60X).

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles