2005 Elantra many codes

I am working on a 2005 Hyundai Elantra... Not sure which way I should go on it. Not running bad, but has many codes..... P0717, P2196, P0170, P2626 and P2271. I cleared all the codes, drove it and P0171 is the only one that came back. Pulled the spark plugsn they are black. And I know a couple of these codes are O2 sensor codes. Any ideas on what would cause code P0171. The owner of this car also told me that when it gets low on coolant it won't stay running. Which does not make sense to me on this car, I don't think it has a low coolant shut down....:screwy: