When was the last time you changed your transmission filter and fluid good possibility the filter is getting clogged I would not use any additives your transmission fluid has a special additive you should change your fluid every 30000 miles filter at every 60,000 if you add any other transmission fluids you will have a problem other than using the Ford fluid
Hey David I'm a customer myself I purchased a truck most likely have you called the dealer they are very helpful they would answer that for you but I believe there are additives that key go to Pep Boys or track auto that they have
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