Check your timing advance (archive)

That is potentially bad. Deteriorating electrodes is a sure sign of pre-ignition. Pre-ignition is when the fuel-air mixture in the cylinder ignites before the cylinder is at top-dead-center. IF the electrodes are gone, it is quite possible your timing is simply too far advanced. However, if only two electrodes are gone, it could indicate uneven heat distribution in the cylinder head (i.e., clogged cooling ports) resulting in high cylinder head temperatures, which can also cause pre-ignition.

Check your timing. Keep a real tight eye on things. I had an engine that ate electrodes for a while, until a full engine failure. Teardown of the engine revealed a hole right through the top of one piston where it gets close to the spark plug. The other pistons in the engine had similar signs of severe pitting on the piston tops.

: I have a 1.8L 320IS 1983. At idle it surges the RPM about 2 to 300 rpm. Under constant load it surges also. Under full excelleration, no surge and pulls real strong.
: I went on a vacation and drove about 1200 miles. About half way through the trip, I disintigrated 2 spark plug electrodes. They were gone!!! ceramic and all. Car still ran though, and not real bad either, just enough power loss to notice. Replaced the plugs and it ran great except the pinging under load.

: Anybody help on this one?

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