JMullen, without more info, i can only guess. Im bettting this happened right after you started the truck,left the shifter in P,threw it in gear,and went to take off. If this is true,then your torque convertor was just draining back. This normal on our trannys especially when they sit awhile or the truck is parked uphill. To keep this from happening,fire the truck,let ir run in N ,the tc will fill in under 30 seconds,putt it in gear and take off. Letting it run in park will not help,it needs to be in N. As for upgrades,if you've got the $$ then go for it. If your not ready to upgrade,but worried about the transmission,get it serviced,by a reputable trans shp,the debris in the pan will tell a story ,they will know if its on its way out.