The fix that has worked well for those of us over here in Ohio and a few other places..(lol) is installing a 5.6K ohn resistor inline with the air temp sensor. It makes the computer see air temps 20 degrees lower than actual.. Which enrichens the fuel mixture and advances the ignition timing.. Providing greater performance... and cutting down on the air temp gets rid of the lean condition with KKM's installed .. The "Heatsoak" is when the engine's heat is absorbed into the intake tracts and induction system.. The IAT then responds to the computer with an astronomically high temp reading that thoroughly leans the mixture out which hurts start up performance and drivability until it cools.
The above resistor can be found at Radio Shack for about $.50 for a 5 pack.
Dom
