Have you clicked on the Modification history Tab in the tuning tool??.
Did you know everything you change is automatically updated and saved?.
You can search by date or keyword.
For example, if you changed the Idle Airflow table at some stage but you could not remember when or by how much, you would simply enter the table number 'B4307' into the search box and it will find it in the history list, then you can see when it was modified and by how much!!.
Don't forget the comments tab too!!.
Cheers,
Ross