7mgte ENGINE IDLE PROBLEM>>>>>HELP PLEASE

[pei09]

HI-

Okay here's the deal my 7mgte has sat on jack stands for sometime, 6 months. I have replaced the inner-cooler, turbo, header, exhaust and thats about it. Now before i put it on jack stands it would rev up to 2000 rpm then die down then rev back up. Now I thought it was the old dirty airfilter. So I replaced that with my other replacements. But i fired it up recently and it still does it up and down. I tried advancing the timing becuase it wasn't sitting at 15 degrees btdc (before top dead center). HAVE ANY IDEAS??? I was thinking maybe o2 sensor? HELP

thanks for reading-

pei09