I noticed you’re using metric data. Do you mind if I ask where you’re located?
I’m also wondering if this is all city mileage. 190,000 kilometers isn’t much for a Toyota engine, and that low a mileage makes me wonder about the driving environment. 190,000 km in the city can be the equivalent of 450,000 kilometers if it’s all city driving. The engine could be just plain worn out even though the total mileage seems too low.
I have to agree with Steve on this one. His post describes my suspicions totally.
As regards the stuttering, a worn out engine will have uneven & low compression readings and excess oil being consumed will coat the sparkplugs with carbon (perhaps even wet oil), as well as leaving carbon deposits on the valves, causing them to stick. In addition it can clog up the throttle body through ingestion via the EGR system and even due to oil being drawn into the throttle body via the positive crankcase ventilation (PCV) system. It can also foul the mass airflow sensor (MAF) and the upstream oxygen sensor, both of which send signals to the ECU to meter the fuel. All of these things, or any one of these things, can cause erratic operation (stuttering).
I could suggest a number of analytical checks, but I truly think you’d be wasting your money. They’d just serve to confirm what your mechanic has already told you.
By the way, I tip my hat to him for his honesty. I know of shops that would clean your wallet out and only then tell you the engine is shot. This guy sounds honest.