Help with intermient limp mode. Code P1751 Code 54

Question

99 Montero Sport 4x4 3.0 in limp mode with check engine light on. Scanner pulled one code ... P1751. Did the manual code trick jumping pin 1 and 4 and pulled code 54. Fluid level ok but was just about black. Have done a fluid change and replaced the A/T Control Relay and still in limp mode. Would a super dirty clogged trans filter keep it from operating correctly