Fmi 157 spn 18

[marek4792]

what year and model is your engine? demandated? could be a couple of things since you seem to have eliminated the biggest and most costly culprit.
could be any of these things if you have insite you can do a fuel rail pressure test to make sure you don't have a leaking injector, or pressure relief valve or sticking fuel pump actuator, or even a fuel line that isn't tightened enough which sounds most likely..