1998 Isuzu Trooper 3.5L V6 Automatic

I''m getting a P0430 check engine light, banks 1 and 2.
I just installed new O2 sensors (oem) and started using 92 octane gasoline from 87 to have a cleaner burn. Could this be the problem? Not sure if this was a good idea.

I did check the possible causes :

<ul>[*]1. The catalytic converter is no longer functioning properly...maybe, truck is almost 10 years old
</span>[*]2. An oxygen sensor is not reading (functioning) properly...new O2 sensors installed (OEM)</span>, so I''m ruling this one out.[*]3. There is an exhaust</span></font><div style="position: absolute; z-index: 4000; top: -32px; left: -18px; display: none;" id="preLoad1">http://kona.kontera.com/javascript/l...rey_loader.gif</div></span> leak...don''t see or feel any leak on the exhaust pipe when visually inspected.</span><br style="font-weight: bold; text-decoration: underline; color: rgb(153, 0, 102);">[/list]I reverted back to using 87 octane for about 1 day now...crossing my fingers 0430 code goes away.[img]smileys/smiley6.gif[/img]

Thanks for any info.