I think I have a leaky fuel injector.

Hard start, especially when warm, better at cold and fine when immediate restart.
Without a gage I KNOW pressure decreases with time at the schrader valve on the fuel rail.

Did NOT help:
replaced "o" rings at injectors (and amateur cleaning of injectors- low pressure air compressor, brake cleaner and 12 volt DC)
New fuel filter
new fuel pump (pro-active maintenance)
engine temp sensor

If I turn key to position 2 and pause (fuel pump runs) and then crank I get an immediate start, so I believe one of my injectors is leaking. How do I know which one?? No error codes on OBD

Looked into replacing all as a set, but hefty price.

THANKS!

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2004, X5, 3.0, 202k+