04 6.0D Throttle position sensor

[HowarD2]

Recently on two occasions I pressed the accelerator clear to the floor with no response. After shifting into Park then back into Drive it drove normally for about a week. Now it has stalled out and was very stubborn to restart. Once running, the accelerator will sluggishly rev the engine while in Park, but in Drive, will not respond. TPS sensor or something else?

2004 F350, 6.0 Diesel, 75K miles, no mods, well maintained.