i have a 2000 f150 4x4 extended cab flair side with 103,971. I had the tranny flushed at 100,000. Since then i have had on occasion a flutter in the shifting. I cant duplicate the shutter but it happens at highway speeds 60 65mph. When i let off the throttle the truck feels like i down shifted but the rpm's dont shoot up, i dont loose power. I can shift manually through all gears up and down and no jump or flutter or slip! Another question is where is the perfect level forthe fluid? My dipstick with truck off is about four dimmples above the cold line. Should i add more?

 

That is not the proper way to check your fluid level at all!

Your truck should be running and in park.And the oil should be warmed up to proper operating temperature.
Only then should you check your fluid level. Any other way will not give you the proper reading.