Hondata

my car has started to not idle on start up, it will start and run at 2000rpm then drop slowly then just stall.
its on itb's and has been sat for 3 months doing nothing

Which version of S300 do you have (V1, V2, V3)

v3

I would start by checking the map sensor because from the datalog I'm not see the map sensor reading change

Map sensor not connected it doesn't use it. I'm running itb's without a vacuum chamber

You must have the MAP sensor connected.

It hasn't had one connected for over a year and worked fine

I'm guessing it's how it was mapped (I know nothing about mapping)

You should probably take it back to the tuner to have them take a look.