I had a 2011 that did the same thing. In hilly country with ups and downs it would “search” for the right gear, upshifting and downshifting, sometimes many times in a short space of road and usually between 40 and 50 mph. sometimes it would do it at lower speeds and a little more erratically but in hilly ups and downs at those speeds it could be guaranteed to do It.
I feared a full transmission swap or rebuild was going to be necessary but I had a friend who told me that the electronic sensor was probably occluded by dirty or cloudy Transmission fluid. He recommended a full fluid swap with changing the filter as well. He then said just drive it a while after the swap.
I had a Ford dealer do the work about $300 after completion they drove it a little bit and said the problem is still there, but within 100 miles of driving it completely went away and I never had another shifting miss of 3000 miles of driving before I sold it.
Coincidence or causality? I don’t know but it sure seem to work.
Edited by Dmblanch (06/17/21 09:19 PM)
1) 2002 White P71 - 89K miles. 2) 2003 B&W P71 - 74K. 3) & 6) & 11) 2005 White P71 - 54K, 74k, 115K. 4) 2011 Black P7B - 79K. 5) 2008 White P71 - 95k. 7) 2004 Silver P71 - 104K. 8) 2004 Toreador Red LX Sport - 111K. 9) & 10) 2010 White P7B SAP - 104K & 106K. 12) 2006 White P71 - scrapped. 13) 2007 Tungsten LX Sport - 125k.