I had a similar problem with the injector pump on my 67 250 SL which has a separate oil reservoir. It got so bad that oil was being blown out of the IP vent. The extra oil in the IP caused the weights spinning inside the pump to slow down causing a very over rich condition which would cause the car to stall if left at idle for very long. The guys on the forum gave me several ideas about what caused the extra oil in the IP including a failure of the seal between the engine oil and the IP causing oil from the engine to seep into the IP from the engine. I took the IP out and sent it to Jerry Fairchild Industries in California where it is currently undergoing a rebuild. Unfortunately the fix is not cheap as the rebuild will be around $800 and the mechanics work about the same. Good luck!