I just bought a 1991 SL500 and it runs awesome until it warms up, then it hesitates when I go to take off and seems to be running very rich as it smokes.

These cars too suffer from bad wiring.I would inspect wires in wire loom,check every connection.Then you would check spark plugs wires,and so on.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Thanks for the fast reply. I will check all wiring thoroughly. Funny thing is that this started the day I found and removed a mouse nest from the main ECU compartment.