1994 GMC C1500 Engine surging

Hi I have a 94 GMC Silverado with a 5.7 Litre in it. I was driving it last week and when I went up a hill I lost power. I pulled over and it was surging even at idle, my dreaded check engine light was on. I have a code reader and when I got it home found a 44 o2 sensor. I have since replaced the sensor and changed a fuel filter for good measure. Started it up and it ran at idle but when I put it in gear it dies and is surging again. I took my air cleaner and clearance ring off the throttle body and both injectors are spraying evenly even when it dies out. Now the o2 sensor code is back, I checked it over and it only has one o2 sensor in it. Any help would be appreciated