alright, so i got this problem lately where my car pretty much falls flat on its face under 2500 rpm. it will stutter and hesitate and it basically sounds like a misfire. so it keeps throwing a code

p0138 which is high voltage for the second o2 sensor, which means a rich condition. so i pulled the code's freeze data from the scanner at work twice.

heres the readings from the first time

throttle 18%
rpm 2596
load value 45.4%
map sensor 44 KPA
coolant temp 190
intake air temp 100
short term fuel trim 1 -12.1%
long term fuel trim 1 3.9%
(heres where the problem lies i think) short term fuel trim 3 -100.6%
long term fuel trim 3 -100.6%
vehicle speed 38mph
fuel system 1 closed
fuel system 2 n/a

and the second time

p0138
throttle 25%
rpm 2532
load vaule 77%
map sensor 78KPA
coolant 183
intake temp 69
short term fuel trim 1 -10.9%
long term fuel trim 1 10.9%
short term fuel trim 3 -100.6%
long term fuel trim 3 -100.6%
speed 48 mph
fuel system 1 closed
fuel sytem 2 n/a

im not entirely sure how the fuel trim readings are supposed to be, but i was told from a couple mechanics that the ones for the trim 3 readings are pretty far off. the numbers are supposed to balance each other out or somehting like that. i dunno, the sensor is relatively new, as is the cat. i'm open to ideas here, or an explanation of what the trims mean so i can start to track down this problem. its pretty annoying

edit 1996 gsr

 

Which O2 sensor did you replace? Did you use an OEM cat?

The Secondary O2 sensor does nothing but verify the efficiency of the CAT.

 

i replaced both sensors last spring i believe it was, and the cat before that. its not factory, its a carsound cat