Rare for the head to warp on a B23F, but after 22 years the headgasket might have failed. Depending on what part of the gasket fails, your mixture can end up 'enriched' with anti-freeze. Hold your hand an inch or so from the tailpipe with the engine running. Smell sweet? Telltale sign is that one or more of your spark plugs has a 'steam cleaned' appearance.

Take a look at the oil on the dipstick and under the filler cap - is it white and frothy? If the oil is displaced by enough coolant, you risk engine failure or seizure. A headgasket job runs in the neighborhood of $700-$800; an engine swap will be considerably more.