Car is experiencing reduced performance as well as stalling. Assuming these are caused by the same issue is it fair to say it cannot be a relay.
Reason is because, as far as I’m aware, a main relay will either be on, off or intermittent by virtue of being a switch and do not determine amount of voltage delivered etc. therefore it they cannot be causing reduced/fluctuating performance issues such as a fuel pump receiving less power.
Just want to ensue don’t waste my time looking at relays for fluctuating or reduced performance issues.