p0138 help! changed o2 twice and still reads code

[Ben Paka]

I first got a P0038 code and a P0058 code less then a year ago after re-doing my entire exhaust. so i replaced the sensors with better quality ones. the P0058 went away and so did the P0038 but I keep getting a p0138 code. I will clear the code and it is not immediate to send a check engine light because it either takes 30 minutes to show up of continuous driving or immediately as I drive on the second time round. was wondering how I would test the wiring. no rough idle, car starts right up fine, just replaced the bank 1 sensor 1 sensor because i heard that sensor could cause the bank 1 sensor 2 to have bad readings.
I've been looking around and i think it hast to be one of these things:
vacuum leak somewhere (I have no idea where to check if this is the case)
exhaust leak before bank 1 sensor 2(doubtful)
wiring harness problems (I think this might be it whether it is the wiring or a short or no ground; no clue how to look for this)
leaking injector (not sure if this is it)

I really would love some instruction because I'm kinda done with this but still want to try to fix it before throwing in the towel and bringing it to a shop for a $2000 repair.

 

[tommudd]

What brand of 02 sensors , these things only like certain brands

better quality ones does not say brand

 

[Plasterman5000]

Use NTK O2 sensors

 

[blackhawk]

Just check in ngk ntk web site that yours fits in your liberty.....