Fuelling issues, ecumaster classic on sr20! HELP!

So i have a ecu master classic ecu on my sr20, its running 880cc injectors and a standard CAS and CAS wheel.

It currently is running at around 11.5 AFR and anytime to try to reduce the fuel and lean up the mixture it runs great for 10-20 seconds and then cuts out after going into a lean state.

I am pulling my hair out with it and have tried as much as my amateur brain can handle. Any help would be greatly appreciated as id like to hit the dyno soon!

Thanks, Matt

Have you checked to make sure you don't have a compensation table on somewhere that is messing with your fueling? Is the car fully up to temp and running for a couple minutes before you make changes? I'm not super familiar with the ECU master software but i recently just had a very similar problem on an Emtron that had a table enabled I was unaware of, and would go lean and stall after a little while no matter WHAT I changed. It was a fuel compensation against firing events table.