Engine Slow to Start

[Yarisillo]

I have the exact same issue as described! 125,000 miles on the odometer, VVT-i engine. 3-door.

Car will occasionally start only after several seconds of normal-sounding cranking. Have already replaced two muffler parts, had a brand new battery put in and no luck.

It used to be maybe once in five starts that it would do this -- the other times it would start instantly.

Now it's almost every other start. I use the car daily, so it's not a matter of it not being driven enough. Also, this happens in 30 degree (F) weather as well as 95 degree weather, so it's not temperature.

I have not tried waiting a few seconds after turning the key to 'ON' -- does this allow for some extra heating or preparation of the engine? My next step, I guess would be to change the spark plugs and/or injectors.

And I guess the next step after that would be going to a Toyota Dealership? I have taken it to 2-3 certified (insured, have numerous certificates displayed in their shop, good volume of customers) places and they have all scratched their heads and assured me that it can't possibly be the fuel filter (which I guess in the Yaris, is located inside the gas tank!)