Ford F-150 - 1997-2003 :: 2001 - Shudders At Low Speed

2001 S-Crew, 4RW70, 5.4L, 189,000 miles. This started two years ago and first became apparent when I made a hard/panic stop. In fact, the first time it did it I was going to go through a traffic light and hit the brakes at the last second so I didn't actually run the red light. The truck shook like it missed for a second. That was unlikely as the coils and plugs were relatively new.

Here's what it does. When sitting still, in gear and you let off the brake but do not touch the accelerator, the truck will start to move as expected. It immediately shudders as it passes through 3-5 mph and then stops. It shifts through all the gears flawlessly, has no sign of the dreaded torque converter issue. It also does it as you come to a stop- as you come to a full stop and the trans shifts into 1st it shudders just as you come to a halt.

It started doing two years ago and never progressed. It's been the same until just recently when the weather got warm again. It's gotten a bunch worse in the last week and now the truck actually feels like it is idling rough sitting at a stop. (It's not- it's running fine.) But it feels like clutch chatter in a manual. Fluid changes have been routinely done every 30,000-40,000 miles, trans fluid is clear and not burnt, temps are normal.

As I said, it behaves perfectly the rest of the time and even tows my 20' 4,000 lb. boat just fine. Just that initial moment of take-off and at the stop. If I hit the gas when taking off I never feel it. Likewise, if you shift into neutral and coast to a stop it doesn't do it.