The PO125 is probably caused by a faulty thermostat (stuck open or opening to soon) causing the computer to see a colder engine temp than it expects, the PO170 could be setting as a result of that, although there are other possible causes for that. check an verify proper thermostat operation (you'll probably find it malfunctioning) and replace it then clear the codes and recheck, you' have to drive it multiple times afterward to complete all the readiness tests

Fuel trim malfunction bank 1 can be many things but majority of time it's the front o2 sensor. I just had the same problem with p0170 faulty change front o2 and problem went away was running rich. Also boost leaks will cause this problem as well.

Ill try replacing the O2 sensor but i replaced the thermostat, coolant temp sensor and sender. and the code still shows up.[DOUBLEPOST=1412820274][/DOUBLEPOST]Where is the O2 sensor on my car?

I don't know if you fixed the issue but you have two 02 sensors up stream (on the 02 housing right off the exhaust side of the turbo) and one further down the exhaust around the cat. typically its the one right off the turbo..

My readiness monitors wont set after 450 miles of driving 97 GST

^^^I had that issue too so I toke a risk I told the tech about the monitors weren't set to ready. He still scanned my 97 gst Spyder checked all emissios in engine bay and I passed. I knew all about the smog problems with our ecus and surprising he knew about them too.

Well I got the code P0125 gone, I just had to check the EC sensor and sender and thermo and reseat them and replaced the coolant and the code went away. Now just to get rid of the P0170 code...

I was reading it could be (rare) caused if your BOV is not recirc'd but more that likely the front o2 sensor is bad like Shifty and others have said but I dont think you changed it yet.

just changed the upsteam O2 sensor gonna see if i pass.