for like a few weeks now, when starting from a stop it feels like the more i step on it the more it sputters and slowly starts to go (hesitates). i have really only noticed this when the car's gauge is not completley at warm. yesterday the p0037 code came on H025 bank 1 sen2 heater circuit low 1-2 and the second same thing but said pending. i know its the o2 sensor, but this wouldn't cause any problems would it? i have the new greddy se cat back exhaust and it makes a lot of popping sounds. should i be concerned? It just seams there might be a lack of power in my car (could be in my head).

Yes, the O2 sensors I am running this way, so the ECU compensates to make it run for emissions.

This can make your car run like crap because it is too rich or too lean.

Also, how many miles on it? When was the last time you changed plugs? Filter? etc?

2004. 32000 miles. plugs changed last year or the year before under recall