02 Sensor or something else?

I have a 94 Shadow 2.2L and its running very poorly once warmed up. I can leave the warm up 10 min, then after about 2-5 minutes of driving the starts to cut out. I have to pump the gas repeatedly or hold it to the floor hard to keep the car running. If I can get the tranny to shift down, or punch the gas hard to the floor, the car will take off.. otherwise it will jerk and get real sluggish. It wont die however. I can pull to a stoplight and it'll idle fine. Im getting an error codes for running rich, o2 sensor (twice), and map sensor. I have already replaced the MAP sensor, to no avail. The symptoms did subside when i injector cleaner through the car for two tanks, but now its getting worse and the injector cleaner is no help.. The car wont completely die, and will sometimes comeout of it at higher speeds (75mph+)

any suggestions greatly appreciated

it wouldn't be a bad idea to replace the O2 sensor, being that it is recommended that every 50,000 miles, that you replace it. Best way to tell if it's acting up is to get a voltmeter and a paper clip and backprobe the white wire coming from the O2 sensor itself and see if voltage is fluctuating.