IF the cables are properly sized and all connections clean it sounds like a starter issue to me. FWIW you don't need an optima but having one doesn't hurt. I had a optima and got about eight years years out of it. It took a dump on a club tour one year and no one had an optima in stock so I went with an off the shelf from O'Reilly and it lasted about 8 years. Pull your starter and have it tested.

Save a life, adopt a senior shelter pet.
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Name your dog Naked so you can walk Naked in the park.