The first code is a failing oxygen snesor, the second code is an EVAP or emissions system leak and the last code is not on my code chart. There is a P0300 indicating a misfire and a P0403 EGR Solenoid control which is an emission control unit.
There are several issues you are dealing with and some are related to vacuum leaks which would cause a racing idle and the poorly functioning emissions and Oxygen sensor are probably the reason it runs rough. The EVAP leak could probably be fixed rather easily as it runs from the intake manifold to the exhaust. The only way it might get expensive is if the exhaust is rusted out and leaking around where it connects.
I think I am going to give you 2 diagnostic walk throughs that will explain the issues you are dealing with. The emissions issues are probably items that can be cleaned and the EVAP leak can probably be fixed for a low cost. It sounds like the car has a lot of issues as if it were overheated at one time or is operated in a high tempoerature climate which has taken its toll on plastic items and rubber items and seals. It also is in need of a fuel system cleaning which would help clean out the emissions items. You could either take it apart as I mentioned and clean it which is best or get some SEA FOAM or BG44K. The BG is better but costs more and you will have to go to a car dealership to get.
Vacuum leaks are more damaging than dirty or cloged emissions items. However, the sum of these, especially the oxygen sensor, is more than likely making the gas mileage very low and costing money as you drive. So, you might invest in some parts, labor and/or some of your time and clean the intake and replace some of the failing emissions parts and the oxygen sensor.
The diagnostic walkthroughs will give you an idea of which problem is causing which symptom in more detail but more than that it will better explain repair. Just use the links below.
Monday, July 2nd, 2012 AT 1:48 PM