I looked over the msq file and I only see a couple general things. One I am not sure if it is real or just didn't load correctly when I opened you msq, but the setting for overboost rev limit was 0 kpa which is not valid, it should be something like 200kpa or were you want spark cut on too high of boost.
These probably don't have any impact but just observations: the spark angle is low for idle for an L28ET, you have 15 it is more like 23 on the stock setup. The fuel table only has a couple bins beow 100kpa. You will probably want something like 20,40,60,80,100 etc or you will have a lot of trouble trying to tune for cruising which is were you spend most of the time driving on the street. Maybe this is causing too big of a jump and causing some of the problems with it going rich, I am not sure.