I had the same problem. 03 exploder XLS 4x4 auto, 100k miles, had the tranny rebuilt with a new torque converter. A week driving it around, started it up in the morning, I can move the shift lever but it would not engage in any gear: D, N, R, 1, 2, 3. It rev's like it's in neutral, in any gear. I can move to any gear position but nothing, won't engage.
So tranny shop took it back and told me it was a manual control valve. I have been looking online to find where and what that part is, in case it happens again. Anyone know what part this is??? I got it back and has been working well so far.