I had the same problem with my initial build, I was told to check my shocks.
I did and found my spring compression was off a bit. I also did a rebuild to match the oil levels. The problem basically fixed it's self after that. Keep in mind the weight balance too, if you can check the corner weights. (use four scales)
Long story short, check your shocks and recheck them again. I used the Losi tools as well and it can still be off a little bit, but the tool can't assess or fix weight distribution issues.