any hepl for this problem?

I have 2003 trailblazer, is the northface edition (same as LTZ) it has more than 120,000 miles, most of that miles are high way miles (I drive out of state frequently) and I have been experiencing some problems during the last few weeks, I notice that I my trailblazer is loosing power, while driving at highway speed for about two hours it looses power and feels like its heavier on the pedal, I press the gas pedal to the max and instead of maintaining the speed it decreases and the rpm gauge drops at the same time than the speed gauge ,dropping to a max speed of 25 to 55 miles,also a have notice that the temperature rise more than normal when this happen, the check engine light also is on. A mechanic check it for any malfunctions and it came out with no codes , he clear the check engine light and last for about 2 days with no problems , but as soon as that light came back the same problems came back with it,

I have taken my trailblazer to a diagnostic check and they found that "the system is to rich,possible failure is in bank 1 or bank 2" does this mean that I have to change my O2 sensors and catalitic converter?

Any ideas of what may be happening?

Welcome to AF. You need the codes here at minumum, it should be in history and codes should never be cleared till the problem is corrected, many things can cause this, the code is the starting point.

Like Max says, this is a tough diagnosis without a scan/codes. A few guesses? A clogged catalytic converter (common on higher mileage 2002-2003's) or failing fuel pump. A failing FP wouldn't account for a temp rise, but they typically don't show a code with only weak fuel pressure. A clogging cat would cause a temp rise.

Joel