Hi, Im new in this forum hope someone can help me find out the problem of my cars here is some specification : So after a year not driving my car I once drive it again .. it idle rough at the starting, couldnt pass through 4000 rpm so called friend verified check engine code P0130 so he changed for a bosch front oxy sensor in my rx-8 2005. After changing it, the car just got worst can pass the 3500 rpm and sometime I kinda feel a downshift of my car. The exhauts doesnt seem to have an hole on that so maybe the unmetered vaccum leak ? please someone help me.

 

Your idle issues are most likely from one of these:
- Reset fuel trims from a dead / disconnected battery
- Gas quality suffered while the car sat
- Rodents chewed up some wiring
- MAF sensor accumulated some dust

There are other more common issues, but these are easily possible from having it sit for a year.