I have a 1998 Infinity I30 and if it sit for too long I have to step on the accelerator to get it to start. It used to only do it if it sat overnight but now it's everyday and it will happen after only a few hours.
Your fuel filter is the first/cheapest replacement for diagnostics. It needs to be replaced about every 50k miles, and you will get hard starts if it gets clogged. Without knowing if you have any trouble codes in OBD2, this would be my first step.
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