You don't say what size bottle of TF4 you started with, but if I am reading your post correctly, you first diluted the TF4 with distilled water, then further diluted into your "working solution." If so, and unless there is a super-concentrated solution of TF4 of which I am unaware, you diluted it too much. As far as I know, with all TF4 or TF5 fixers, you dilute the concentrate in the bottle 1:3 with distilled water and that is your working solution.
If my interpretation is correct, and assuming your "first" dilution was 1:3, then try some of that solution with no further dilution and see if your film clears faster. 30 seconds is my experience.