You need to ensure you have the radio set up right. That is the biggy for the Losi.
Make sure your shocks are full and your diffs are tight and have fluid in them. I have seen the rear diff back away from the housings input gear. The aluminum inserts help this a lot. I would highly recommend these if you have the time and means.
On the shocks, I use an Xray 4mm reammer to open the upper bushings so they rotate freely on the shock mounts. If you grease them up and then put some glue on the bushing then install the shock over it, your bushing will wear instead of the alum shock tops. It is very effective. CA Glue will only bond the alum to the plastic temporarly.
Read my post about installing batteries in the battery holders.
There is a lot of good information on here. Good luck.
TEX