I have a 2003 Pontiac vibe fwd with 146,000 mi on it. So far, the things I have done to it are all general maintenance spark plugs, oil changes, brakes, tires, air filter, etc. Outside of those, only the intake gasket (Toyota version to fix that cold soak cel) and a mass airflow sensor have been replaced. At this point, the car is starting to idle rough and I'm wondering what should be done at this point? I would like to keep the car for another three years if possible. I do not mind spending a thousand bucks or so to get things done. Should I be doing things like the alternator, valve gaps, IACV valve, coils. If you guys have done these things, about what mileage did they need to be done? Some of it I'll do myself others a local good Indy shop. Why info and suggestions would be helpful. I am planning to do an upper cylinder seafoam treatment through the throttle body, btw.
Edit* all fluids are consistently flushed and filled so they are good.