Background: my 05 MCS is starting to have cold start idle symptoms. Since the weather has changed (colder) the cold start stuttering in AM isn't as bad as summer -- summer fuel mix(?). I've researched and checked most everything mentioned on MA except replacing the fuel filter. Puzzling really. :confused5: To recap that experience: anytime the motor is cold, starts up fine but as is settles to idle below 1k the motor stumbles ever so slightly. If I blip the pedal it recovers fine. Then once warmed up she runs like a champ. Even at stop lights. no codes thrown so far. It feels like the initial cold start fuel pressure or AF isn't right. I rescued this last november off a used lot in GA. It had no history. Not sure if it was tuned and at idle that tune is off (just an idea). I'm in winston so may give Chris Sneed a call. Question: My Q on AFR gauge is that could tell me if the AFR is too lean at start. But might be talking out my arse there -- MA feedback would be helpful thoughts? Thanks.