Missing in gear from idle up to 4000 rpm 4000 to 5000 runs good push stick to wot it starts missing and rpm starts dropping. Yds high pressure pump is 685 to about 730 medium pump 49 psi checked fuel filters vst tank and screen look new yds shows all 6 firing spark checker shows same. Timing at 5000 is 21 Btdc push stick to wot timing goes to 8 btdc . Sent injectors out. Reed valves look good. What do you think