Why my car will not change out unless I get off the gas pedal it will jake as long as I hold the gas and will not change gear?

Your car is entering "Limp Mode" because of a sensor (speed sensor) providing bad information to the computer or a transmission module problem.

water in gas,use drygas

check there are not any splits in your air intake hoses and check the ignition timing is good.

you need a new fuel pressure regulator

my truck starts right up if I hold the petal to the floor but wont start if I don't hold petal to floor

almost sounds like the cruise control is engaging

Check the fuel pressure with a gauge. The pump may be going bad

your kickdown on your throttlebody may need to be reset or you may have have get your trucks computer scanned for any codes, hope this helps

Assuming this is a standard transmission, you always have it in 1st gear. Roll back is controlled by balancing the clutch with the gas pedal.

If an automatic transmission, then the vehicle should hold itself on the incline, unless it is a steep incline, to which you may use the gas pedal to hold the vehicle on the slope, and not the brake. And you would always have the transmission in the main drive gear position.

The tps(throttle position sensor )may be malfunctioning