I have no headlights, dashboard lights, radio, no turn signals, hazards (flashers), the motor isn't shifting right and can't go over 45 mph it won't let me, the the speed odometer, gas, no power to windows but if I hold the brake pedal to the floor everything starts to work with warning lights on?

Gas gauge and speedometer/odometer aren’t working. All fuses under the hood are good and in the proper location according to the truck schematic. As are the fuses inside the truck on the drivers dash. I also notice the truck will stall out at startup if I don’t apply some gas. Where do I go from here?