I have an 04 4.4, and my car is in the dealer now for the 2nd time for the trani slipping. 1st time they upgraded the trani software and, that didn't help. They called me today and, said there's something wrong with the trani but, they don't know if it's mechanical or electrical. It happens mostly when the car is cold but, occasionaly even when warmed up. It's a good thing it's a CPO and still covered or I would be in deep trouble.