I have an 2001 Infiniti I30 with a 3.0L V6 with 85k miles on it. Due to the gas mileage having dropped over the past two years (about 3-4 mpg - city/highway) and due to fuel dilution of over 1.5% (closed cup testing method), I suspect I have one or more fuel injectors leaking at shutdown. The sparkplugs (NGK platinum - 100K mile plugs) were pulled and inspected at 58k miles and they looked good. New NGKs went back into the holes. The PCV valve was changed with no issues noted. So what is involved in determining if one or more injectors are leaking? Removal and bench testing? Any guess as to how much? (I know, independent versus dealer as to price). Since it is baseball season, I'll take a ballpark figure. Thanks.