hello I am new to this. been a mechanic for 22 years. going to do my best at diesels. working for a sheriffs county rigs. got a 2010 for f350 6.4l. did a contribution test, found cylinder 5 and 6 showing at idle and till 1200rpms only. replaced all fuel filters, performed fuel diesel injector clean service. replaced #5 and #6 injectors. let vehicle idle for 15-20min- for fuel bleed. test drive vehicle and runs great until idle only. need help for diag for possible fix. knocks and rattles only at idle-1200rpms.

 

inspected the rocker arms, valve springs for damage and check plastic clips- found no problems

 

I was going to suggest checking the rocker arms and the clips.

What fuel filters did you use? OEM?

 

yes all oem for ford. got all connections for all dealerships.

 

well if the injectors are good and the valves/rockers are good...then do a compression test.