When going uphill at slowere speeds my automatic transmission on my 2003 Mustang Gt covertibel shutters. It only has 15,000 miles on it, but it is outside the warranty period. My local Ford dealer says the shutter is because I store the car for seven months in the winter and that I drive it less than 5,000 miles in the summer. They added XL 3 additive to the transmission fluid to help combat the sediment that they say is built up while in storage. They said that replacing the torque convertor would not help. Do you have any receommendations or suggestions on what to do next?
How does the fluid look? I guess we can assume that they would have replaced it if it looked bad. OTOH, if it looked bad at 15K there would be something wrong with the trans.
I don’t buy anything the dealer told you, storage, sediment, bah. I would be tempted to replace the trans fluid. Make sure they they use the correct fluid. If this is a GT with the 4R70W or 4r75W that would be Mercon V. I don’t know with the V6, but it is probably the same. Your next step would be to ask friends and associates if they know of a good transmission specialist.
BTW, that is shudder, not shutter.
You might check the Crown Vic board. This was an issue with Panthers which share the power-train with the Mustang V8. It’s a torque converter issue, and there is a cure…