Lower-income Americans sharply reduced their gas consumption in the month following the Iran war, yet spiking prices still forced them to spend more at the pump, worsening the economy’s disparities, new research released Wednesday showed. Higher-income households, meanwhile, ratcheted up their spending on gas while barely reducing their consumption, according to a report from the Federal Reserve Bank of New York. Middle-income households fell in-between. The figures suggest the gas-price surge has worsened what many economists call the “K-shaped economy.”