I have not driven my truck in a few weeks so I charged the battery and went for a drive. I tried brake boosting in 4wd several times and it would launch hard then fall on it's face every time. It has never done this before. I kept the accelerator to the floor the whole time and it just slowly increased speed like normal acceleration. This is an 02, so its not the throttle body closing. Any ideas?

Thanks

 

Afr and timing normal when this happens?

 

I did not notice. When I get some free time I will try it again and log it as well