i had this exact trouble last weekend. my oxygen sensor even though only 14 months old died and caused terrible idle and no power.

to verify besides measuring voltage, disconnect the o2 sensor wire and the 2 heater wire2 with car OFF..... and then run the car. if it runs and drives better replace the sensor.

verify by heating up the engine and then checking sensor voltage off the black wire under the rubber boot passenger firewall..... normal is rapid vacillation between .4--.9 volts with odd spikes higher or lower

a sluggish response of much lower voltage to zero voltage means you need a new one.