y does my temp stays on the 3/4 mark but i press the gas it goes back 2 normal

What is your question?

i by pass the heater core cause it went out on me., every since then i been having a problem with my temperature.. so i took the thermostat out and re-fill the car with coolant it did find until the car sat still and the temperature went up but stays on the 3/4 mark.. but soon i raise the engine 2 1500rpms my temperature hand goes back 2 normal