J33NO

Just purchased my first Z: 06 Roadster 69k miles, all stock except aftermarket wheels. Was owned by a 74 year old man that hardly drove it so its super clean. 3 days after getting it I get a service engine soon light on. Run the code get a P1084 code which apparently points to the exhaust valve sensor in bank 2. Replaced that, reset the code, nothing. SES light still on. So found a post on here with someone saying they had the same code and replaced the intake sensor in bank two (Green - straight sensor) instead. I replaced the intake sensor and my check engine light went away, car went from 1100 idle down to about 500/600 idle and almost immediately I could tell a difference in the way it responded. It felt much quicker and seemed to be more like it should. 3 days later, it seems to have gone back to its old ways and feels sluggish again. SES light hasnt come back on, but it feels like its back to how it was when I got it which is different from how it felt after I replaced the intake sensor. Any advice on where to start or common problems would be much appreciated. Thanks!