I bought the 99 f150 about a year ago. I had the tranny serviced about a month ago for peace of mind. Just asked them to change the filter, and the fluid. The truck does have a tow package on it, and has pulled our tent trailer quite well.

However, on the past few trips, we notice the engine seemed to be revving faster when starting off, and then on the most recent trip, we noticed a rumble or vibration when letting off the gas at around 65 mph. The truck would smoothen out when accelerating again, but would rumble/vibrate again the moment I lifted my foot off the gas. Any speed lower than 50 and it would seem to run fine.

When we got back to town, I checked the fluid level and it was maybe a half litre over filled from the service. My concern is they may have either put the wrong type in, or the fact it is over filled. What is the best way to drain a half litre of fluid out of a tranny? And would that contribute to the rumbling/vibration?

Any advice would be greatly appreciated before taking it back... to maybe have more damage done. I do not trust many service stations.