Jeep Struggling To Start

2005 Jeep Liberty 3.7L V6, 131,000 miles

When my jeep is warm it struggles to start, earlier it shook the entire car and eventually started, when I stopped it wouldn’t start again until I pressed the gas. After sitting for probably an hour or so it started perfectly fine. I recently upgraded my sound system but my alternator is above 13v under load when idling.

Once it starts, it’s able to idle just fine and doesn’t stall or anything else.