im thinking of buying a 87 560sec with a brabus pkg. on it.everything seems to work fine except for the fact that the car is puffing black smoke (enough to leave a stain on the driveway after a few minutes). the owner tells me that a mechanic overtightened the fuel distributer ,and that it has to be replaced.
what damage could it do?clog the cats?
is it a cheap fix?
what else could it be?
the car has 270 000 kilometers
thanks in advance

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1992 500E silver
1990 300ce AMG
1993 500e smoke silver-sold
1992 500e sold pearl black-sold
1966 mustang converible 289
1969 camaro x11
1991 ZR-1
1972 corvette roadster
2000 dodge cummins 4x4 sold
1994 e320 sold
1987 560sec Brabus
1987 300E (my first benz)