I need more advancment of the ignition timing and the distributor is at it's limit. The only thing I have not replaced on the engine is the distributor and a wrong exhaust valve spring that came with my re-built machined head. My vacume reading is showing ignition timing late and it is pulsing. I think the pulsing shows that there is a week cylinder. And like I said I found one exhaust spring that seems to be week and the wrong one for the head. I have a new spring from honda and was wondering if I need to replace the distributor since this seems like a vacume and map sensor error. Like as in the map sensor readings are telling the ecu a mismatching engine load conditions and so I can't set timing becuase it is retarding it. Any ideas master techs?