Was driving down highway going about 60/65 mph. Then the transmission shifted from 6th gear to 1st gear very rapidly. Was able to pull over to side of road and truck repeatedly jerked while shifting back into 3rd then back to 6th. Truck drove normally for a while afterward and then it happened again when driving roughly 40 mph. This seems like a major safety issue considering downshifting 5 gears suddenly reduces speed quickly and can cause an accident or loss of control. It seems something with the transmission is the issue. It is available for inspection if requested. Theres been issues with the gears shifting incorrectly and when taken to ford they just say they dont know what Im talking about and give the truck back but its pretty obvious when driving that theres a transmission issue. However this is the first instance where it shifted significantly when driving at a high speed. The check engine and wrench lights popped on when the incident occurred as well.