Over the past 2 weeks, my 06' 350z has been acting up engine wise. There are no definite check engine lights, but when I prompted the computer with a scanner, it gave me the P1078 engine code. Some of the problems I've been having include: a shaky/unbalanced warm startup (low rpms, ratlting, and sounding like it might lean out and die), a sort of chittering from 2.5-3.5k rpm when accelerating in gear (again only when warm), very sub-par fuel economy, and more engine noise than i'm used to when parked and idling. I recently changed the oil which originally fixed the same chitter that I had around 4 months ago, and its sitting at 130k kms. I have heard that spark plugs/timing chain issues might be the source of the chittering/extra noise (which are still oem). For mods, I only swapped a different muffler in maybe 10 months ago, which hasn't been an issue until now. I kept all of the oxygen sensors and catalytic converters, as I didn't want to cause a big change in exhaust backflow, but maybe now it's the issue IDK. Any possible solutions or next steps of action would be really helpful thanks!
