Yes my 98 m104 engine,studders when giving full throttle when engine is warm.I had a large hose fall off air pump,i reconnected,and it runs a little better.Trouble is too,when I remove oil cap,when engine is running no change in idle.I do have vaccum to fuel regulator,but I don't believe its enough,should it be 16 psi?I've felt every vacuum hse,sprayed carb cleaner around connections,intake manifold gasket,where plastic manifold joins aluminum part,no change in idle.
I thinking can that large round valve near intake manifold be sticking open.Called a air pump check valve?

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt