what would cause erradic shifting on a 2003 Aviator? on 2003 Lincoln Aviator

The tranny has been serviced and fluid changed. At times it shifts normal, but ither times it is late shifting, hard shifting or feels like I am "towing" something.

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2 answers
My 2003 started doing this over a couple of months and suddenly at the bank drive thru, it would shift into all gears but would never engage. Repair was to the shifter cable and cost me $160.00.
sounds like you have a solonoid in the trans going bad