The diffs where rebuilt before installed since they had no oil in them at all Ididn't keep the belt all the way loose, but was loose compared to factory setting. Would a bad soldered connection cause the truck to run sluggish? Someone said that Icould have a lead connected wrong, but Ithought brushless motors had no polarity so I kinda ruled that out. I'll change the belt tension and see if that helps on a few jumps the truck also seemed to just die (thus reason for thoughts of a bad connection).