I recently got my truck back from the body shop after being involved in an accident. They had to replace the transmission cooler since the front end was damaged, and I made sure they knew to use Mercon V. Well since Ive gotten it back, at WOT(or heavy acceleration) the transmission does not shift smoothly on the 1-2 shift. It jerks and then shifts into 2nd, almost like the engine hits the rev limiter. Also, the engine seems like it lacks power. Of course it could be because I've been driving a Monte Carlo the past three weeks, and this things a slug, but it still seems to lack power. I was trying to pass on the interstate and a Titan pretty much handed me my **** and beat my to it. That was embarrasing.

Anyone ever had issues with the hickup on the 1-2 shift?

 

Make sure the fluid level is good and full it could have lost a little fluid.
Alan

 

I'd be calling the insurance company you dealt with.

 

Here is a vid of my truck with only a 77 series intake it had a bad 1-2 shift the tunes fixed that.
http://media.putfile.com/KN-with-stock-exhaust-0-60

 

I'd be back at that shop. If it didn't do the hard shift before the accident, then it shouldn't afterwards. They need to look at your truck again and fix the problem

 

I double checked the fluid level again and after driving a couple hundred miles it was about 1/2 qt low. I topped it off and drove another hundred miles and tried a couple WOT 1-2 shifts and it appears to have smoothed out. I wouldnt think a 1/2qt would make that much of a difference. I will let you know how it turns out.