I would check the fuel pressure next, whether that be a cheap gauge on a piece of hose taped to the windscreen or a fuel press sensor connected to the ecu will be fine. What you are looking for is the fuel pressure should increase 1:1 with boost pressure. So, say you have 43psi fuel pressure at 0psi boost, you should see 53psi fuel pressure at 10psi boost and 63psi fuel pressure at 20psi boost.
Do that and report back. Obviously you will have to see some boost to do this test but I would highly recommend you dont give the car a hard time until this is diagnosed. If it doesnt increase 1:1 then there is a fuel supply problem and that could be a large range of causes which we'd then narrow down with further tests.
