[quote="Podunkfla"]Heikki... Yep, Leon is right on with his assessment given what little we know from afar. The O2 sensor often does sort of wear out rather than just quit. Next to look at prolly is the temp sensor (cold water sensor); when they go the engine thinks the car is still warming up all the time and sends a rich mixture. If your fuel mileage has gone down, that would be a good indicator. Usually the only sure way to find out is to pay for a diagnostic test to tell you what isn't working. Down here in Flada, with no inspections, I only have to worry about fuel mileage and running issues. So when I do a tune-up it's cheaper to just replace the most common culprits... Rotor & cap, plugs & wires, O2 & temp sensors. That usually costs about $100. I find it is often cheaper to do that than pay for a diagnostic on an older car without an OB2 plug in for the newer diagnostic computer.
Good luck buddy... been there.
~ Brick
Leon and Brick
There are no real symptoms while driving or while engine is in idle, except.. at first when starting it.. the engine tends to have higher Rpms than after warming up..
I,ll start by doing the rotor and cap and spark plugs and even new wires and ...and timing...as you mention.. sensor..
And get rid of it.

before next inspection which is next June.
Classic Finn