Americans at the low end of the income rung are once again struggling to make ends meet. A confluence of factors — the expiration of federal stimulus checks and surging inflation on staples like gas and food — are driving an even bigger wedge between the haves and have-nots. While wealthier shoppers continue to splurge, low-income shoppers have pulled back faster than expected in the past two months. They’re focusing on necessities while turning to cheaper items or less expensive stores. And they’re buying only a little at a time.