1969 280 SEL vacuum leak problem?
 

My 1969 280 SEL is runing on 4 of its 6 cylinders it seems. The compression checked out with 150lbs. of pressure in all cylinders. However, no changed is detected in running when spark plug wires #1 and #2 are removed. Is this a good indication of a vacuum leak? I sprayed carb cleaner all around the affected area when the car was running and it didn't seem to change the engine beat at all. Any other tests I can run here? Many thanks.
Thom