just some things to look for if your having these problems?(tight erave cables/dirtyrave valve) if the raves arn"t fully closed when first started the ecu senses a problem and puts the fuel system into rich mode.(low octanefuel) ecu knows there is a fuel problem by means of the knock sensor and puts the fuel system into rich mode also.(stuck injector /dirty injector)will also make it run rich .high ash oils are also another thing you don"t want to use with the sdi motors.(bad/fouled plug)another thing to look for.(up dates done incorrect/06to06orback to05)we have found it takes 7-10 times to get these updates installed correct.the cold start update isn"t as time consuming as the ecu updates.(rave cable adj.) we have also found it takes 4/5 trys to ge it correct and if you don"t run the engine over where it needs to cycle the raves and then shut the engine off to see if the raves are fully shut you will never get rid of this over rich problem!the servo motor must be able to reset itself when ever it cycles or the ecu will know and you"ll get that exsessive fuel problem.(bogging)a stuck rave valve(open)would cause this problem.just some things to maybe help those that are having these issues?this is a good motor but it seems alot of techs haven"t figured out how to do the fine tuning this motor wants yet and with the lack of snow its only made it that much harder .good luck!!!