Have a 3.3 with a tune slight rich . Idle as low as possible but still tends to move when I stay it . High rpm when I lift off the grown as the wheel spins and dies when I brake .
If it isn't a clutch problem, as @mrbones suggests, it could be that your HSN is rich but your LSN is lean. The LSN controls the idle and takeoff and the HSN is the WOT. Too lean on the LSN will also cause it to run too hot even if it's just idling.