Hmm... It may not related but I thought I'd share my story. I stopped by one of those quick oil change garage. I haven't changed my oil in the last 5 months. The mechanics went over a couple of things and convinced me to do fuel injector service, because he noticed rough idle when he was pulling in the car. He removed the plastic pipe leading to the throttle body, added someting to the gas tank, replaced the fuel filter, and hooked up some kind of cleaning agent to the gas line going in to the fuel filter. Using cotton swap and cleaning spray, he hand cleaned the inside throttle body before firing up the engine. Slowly the cleaning agent went in a little by little, and the engine rumbled like a caged chicken. About twenty minutes later, it was done, and when he reconnected the gas line to the fuel filter and started the engine again, I couldn't believe how smooth it sounded; I was occasionally expriencing fluctuating idle and sudden surge of RPM out of no reason. And it's all gone now! As a matter of fact, I'm going to take my finance's car tomorrow to get the same service done. Up until today, I simply thought I'd need major tune up done to my car, but it only needed to be cleaned thoroughly. Maybe that's all your car need too. I'm sorry this was rather long but hope this helps.