Car needs so much help...

[99GTKid]

My SES light has been on and off daily. i ran it with the computer and got multiple codes including

-Injector Circut Open Cylinder 3
-Cylinder 3 Misfire
-Camshaft Position Sensor A Bank 1 range/perf
-O2 Sensor Heater Circut Malfunction
and im pretty sure it repeated the third code as the fifth for some reason.

Is there anything I personally can do with my not-so-extensive knowledge of mechanics. I mean i can do my fair share but damn. Four codes cannot be good. Help is always greatly appreciated.

[GrandAmC9]

bring it to a mechanic and see what they say needs to be done, if you feel good about doing the work do it, otherwise let them do it

[350rs]

fixing code one will fix code two. sounds like it may have come unplugged? were you messing with anything under there like that? code 3 is an easy fix, dont know about cost however. and same with 4 there. sounds like its just a bad o2 sensor. how many miles on the car?