Ranger GT500

The engine has ample power to pull the car but drives with about 20hp less than it should. It idles fine but sputters as you accel. No knocks, no pings, no sounds of vacuum leaks. When the computer was read it said there was a miss on all 4 cylinders. Car literally just did this one day when it started. Will run the rpms just as normal. I assume O2 senser but i need help. Lil bro is about to get job at pizza hut driving and he needs it to run better. Thanx guys.