1981 Mercedes 380 SL, poor acceleration cold,no power and just about stalls,gets better warm,has a high idle when engine is warm. Sprayed carbureter cleaner into center air valve and idle increases, and at the right side rear intake manifold. Has anyone seen this concern before? Leads toward a vacuuum leak,Has there been intake gasket problems found and I look at the parts and they sell right and left side intake gaskets.