At the moment my Soarer TT has the same problem by the sounds of it. I've done alot of K's in it (194,000kms). On most cold mornings, black smoke comes out of the exhaust heavily, and when driven, it "stutters" and smokes. At idle every 2 or 3 seconds the engine "skips". Once warmed up it usually runs fine, except for an ocassional puff of black smoke when it is floored. It can still easily show up a new Monaro or VX Clubby, but its a little embarrasing when they point out later that it looked like there was a fire underneath my car!!! Any suggestions???