OK so I have an 05 636. She has a cleaned K&N, new plugs, oil change, radiator flush with engine ice, PC3, Driven block off plates, Yosh slip on that has been cut 3", new chain, new clutch cable... So as of recently her mpgs have dropped to 90-100. She was running rich a little while ago and I ended up taking zip ties to every connections on the vac lines. That took away the rich smell. I'm just stumped. Any help please.... I have a feeling that I need to do the valves soon. She has around 32k on the clock. Thanks in advance.