no heat until I kick the gas pedal down any ideas?

Let the vehicle warm up at idle without driving (or reving up the engine) to activate the heater. Check the heater hoses when the truck is warmed up. They should be hot to the touch. If both hoses are cool, check the heater control valve, it is probably stuck. If the inlet is hot, but the outlet is cool, you most likely have a restriction in the core. If both hoses are hot but still only cool air, check the blend door operation in the cab.