2005 f150 5.4 original owner, transmission was replaced at 90K due to complete failure, now at 148K I'm getting a slip especially when it downshifts from OD to 3rd. Only a second or two but a noticeable slip. Because of this I dropped the valve body thinking it might be the overdrive servo but it was fine but replaced it and the snap ring anyhow. I also checked all the springs, replaced check *****, replaced the valves with sonnax, and put on a thicker separator plate. None of this has helped. Per phone call at local trans shop he thought it was 3rd gear clutches and would be 4k to rebuild. I'm thinking it's something else.
I KNOW its not a misfire as I also just did a timing job and I replaced every coil and plug on the engine. No codes are present. Any ideas would be appreciated
Trans Code B, 4r75e