Could be the starter. Though the 3.7's don't have many issues with this. But, sounds like a starter to me.
2006 GC Limited, 5.7L HEMI, Quad II. 4XGUARD Belly & Front (black powder coat) skid plates. Matrix front guard, PIAA Matrix mounted lights, 265/70 Nitto Trail Graplers MT, 1.5" Spider Trax spacers, Super Chips Tuner, OME MD Lift, 4XGUARD differential guard, JBA UCA'S.