That's the funny thing. There is no error or check engine light.
My car behaves almost the same way. Sometimes you find it very stable, no vibrations etc and not very loud. You go to market thinking my car is behaving very good.
Then next day you have to do some running around, about 20-50Km running, putting full weight on it and it goes through it all. You are happy about it, and then while returning at evening you tend to stop at a signal and all hell breaks lose. Heavy vibrations, miss fire, jerks while accelerating etc. You somehow reach home, and search endlessly on internet about what could be the problem, check everything in car which seems normal. The next day, it's again in peak condition leaving you wondering what the hell is this thing's problem. All these problems appear when the car has gone through some stress, that's what I figured.
So far, I have tried everything. replace throttle body, Change all fluids, replace plugs and what not. The list is endless.
Interestingly, the car was absolutely fine earlier. Then my mechanic did some regular maintenance and since that day it has not gone back to normal.
My ultimate thought is busted ECU. Unable to learn your driving styles and adapt the correct settings.
