Other than; fuel pump, fuel pipe, filters being clogged, fuel regulator / connection to inlet manifold or fuel / surge tank pressurising is there anything else that could prevent fuel pressure rising as boost comes in? eg amal valve, ecu, chip, map sensor etc.? engine is 2wd cosworth running amal valve, standard fuel regulator, level 6 ecu

thanks in advance

P.S. this is driving me mad...