Hey guys i have a 03 supercrew with the 5.4 engine in it. It has about 84,000 miles on it. The problem is when i am cruising down the road and give it gas to pass someone it make a hard clunk and shifts really rough. it only does it when it kicks down maybe 2 gears basically wot. It will always do it around 50mph up to 70 mph. Any ideas what it could be the truck does fine except for this problem?

 

Mine does the same thing but i have 350,000 miles on it. My clunk has been there since new and my tranny is the original. So i wouldn't worry to much