OK to start off the truck has 240k on it and before I tell you what it is doing I have worked on trucks all my life. So this is really blowing my mind. No Chevy or ford has ever had this problem. OK it gets stuck in overdrive and will not shift out unless you put it in N or give it fuel and if you don't it will try to push the truck. Now that tells me at the lock out in the torque converter is sticking. But here is the kicker when you hit a bump like rail road tracks it acts like something gets thrown out of balance so bad it is like you broke a drive shaft. It shakes the whole truck. When you put it in neutral and stop then start back off it is like it never happened. And it mite only do it one or two times a day. I have checked all the drive shafts and u joints and can't find anything wrong. And I have never had anything like this happen and still be able to drive it with out fixing something. Maybe someone has had this happen? ?

 

It sounds like death wobble to me check tie rods and especially the track bar I just got a 1997 3500 2 weeks ago and it had some bad death wobble and it was my track bar thats what I would check first.

 

I will check them today.

 

X2 on the Trac bar

 

Thank yall track bar was the big problem. Now to put the twins and injectors I have in.

 

track bar is the most likely issue

 

What kind of trac bar did you install??