Trunk well not open totally on it own on 2007 Hyundai sonata I put new gas stunt

Hello, This is somewhat common. The support struts are there to hold the trunk lid open, but they do help in opening the trunk lid by slowing it to prevent wear on the hinges. Underneath the rear cowl (where the speakers are mounted), there are torsion springs that are just little rods that go from one side of the trunk to the other. These are the culprit if the trunk will not lift on its own. There is an aftermarket solution available if you google the issue of worn trunk lid springs.