well if your finding oil on ya spark plug I would go down to genral Maint section and post that, that cant be good, but if its just on the threat? dunno, as for ya injectors, I would take them out clean them, or go get like 3 bottles of injector cleaner and run them threw with every 1/2 tank or so of gas and try to flush the system, another thing is did u install the fuel pump right?