2000 ford f 550 v-10 p0303, p0304, p0308, p0309 codes what could help narrow down the problem

Question

ive changed fuel filter and flushed fuel system on trk also had to change exhaust manifold studs

Answer 1

Have you replaced the spark plugs recently?if not replace it. check to see if the ignition coils are working. Add 91 octane gas from Shell with a good fuel additive (chevron with techron fuel system cleaner) Not fuel injector cleaner.

you can also check for intake leaks