2nd3rd4thgen

i have a 93 z28 and i ordered a tune from pcmforless. it asked me to tell them about any trouble codes i have. well my ses light doesnt come on often. well i drove it around for a few days and i finely got a trouble code so i got out and checked it useing a paper clip.it showed a code 13 o2 wireing code on the right bank, a code 32. egr which is removed and a code 63 same as code 13 just on the left bank. then i reset the codes. then i went and put it on the order sheet and ordered the tune. well when i got back in my car and took it for a drive a few miles down the road the ses light came on again. and went off. i reset it again and drove a few more miles and it came on again this is weird because it usaly doesnt come on verry often maybe once every two weaks or so but now its coming on more often after i check the codes. my tune hasent come in yet but i just thought it was kinda weird its coming on more often.