Hi. Not had my rs turbo long. Anyway decided to change the oil and filter. Refilled oil as ive done a million times. Started the car up and it sounds like a subaru! Very very badly misfiring. It ran fine b4 i changed the oil. Ive checked the injectors and they are spraying fuel. The fuel pump primes. The plug leads are new magnacor jobbies. The plugs are very black and sooty though and there a month old. Please help someone. Cant understand how changing the oil caused the cars poor running. Im on mfi engine.