Hey everyone! Long time peruser, first time poster.
Anyway, I have an 06 Vibe Base AT FWD with a little over 185k on it. I've been having a weird intermittent starting issue for a while. In it's current state on a warm day with a cold engine, when starting it takes a little bit to start to which it stumbles to life like it's getting too much fuel or the like. If I shut it off and restart right away it's fine. I've replaced the intake manifold gasket, the MAF sensor with a Denso brand, the PVC valve, new Wix air filter, NGK coils and plugs, fuel injectors, and both upstream and downstream O2 sensors with Denso brand(as they threw a code). Also cleaned the throttle body when I replaced the intake manifold gasket. All of these parts have been replaced over the last year or so. No check engine light currently.
I'm mainly wondering what I should try next. Car runs great after it's started but gas mileage is down a bit. Replaced the air filter most recently(a few days ago) as it was overdue and haven't refueled again since to see if gas mileage has increased. Any help is appreciated.