i have a question? i have an 04 RL and i juss noticed today when im doin about 40 or more and put it into neutral to coast and my revs on my tach drop to about 400 then to 1000 then back to 400 and then up to to 1700. it does that till my car slows to about 5. does any one else have this problem? and does any one know what it is. cause my 71 blazer doesnt do it or my work truck.