Classic Hard Start for 2000 S40... Not fixed by classic solution.

[kfergiez]

I have the classic hard start issue for my 2000 S40, but it is not fixed by replacing the fuel pressure regulator. Symptoms are as follows:

1 - When engine is cold, it will crank for upwards of 10 seconds before reluctantly coming to life.
2 - After starting engine runs fantastic. No hesitation or stalling. (See caveat on #3)
3- After driving a couple of blocks, engine will rev up slightly with light or no throttle input... causing sphincter tightening if coming to a stop.
4 - Replaced Idle Air Control Valve a couple of years ago. (I don't think this is the issue since the fix for this was to simply hit the gas a bit)
5 - Replaced the Fuel Pressure Regulator. Had no effect.
6 - Let fuel pump run before cranking (to see if lack of pressure at the rail was an issue)
7 - Spark plugs look great.
8 - Fuel pressure and flow rate are great.
9 - I have a P0118 and P0128. Are these related to issue? I've had these codes for a long while, and this hard start issue appeared out of thin air last week. I'm going to replace the thermostat and Coolant Temp sensor tomorrow.

Any help would be great!

[difflock54]

Check your IAT sensor. ( inlet air temp sensor )
That effects the fuel mixture and can make cold starting difficult if its not working properly.