95 Dodge Neon w/ codes P0134, P0401, U3FFF

I have a 1995 Dodge Neon w/ a 5-speed manual transmission that I drive to and from work. My check engine light came on and I got three codes from it:
P0134- O2 Sensor CKT No Activity (bank 1, sensor 1) P0401- EGR Flow insufficient U3FFF- No DTC Definition Found
The problem I am having occurs about 30 min into driving the car, from a cold start. It loses acceleration(in second, third, fourth and fifth gears), sputters and if I pull over, the RPMs drop below 600 and the car starts to sputter, like its going to just stall and die. If I turn it off, and back on, the RPMs rev quite high (up to 3500 in some cases). I am usually at my destination in 30-60 min and after it sits in the parking lot, it starts up fine, sounds normal, doesnt have any problems until about 30 min into my drive home...
I would like to repair/replace any parts myself if possible, but if not, would like to know which code might be causing my problems so I can get it in and out of the shop quickly on my days off. Any help would be greatly appreciated.
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02 sensor code could cause a surge while driving and if it shorts out could cause other problems as well. The proper way to diagnosis this would be to have a scan tool connected and systems monitored.
Glenn Beasley Chrysler Tech
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