intermittent smoke and misssing

Hi; Just bought a "fixer" 94 Suzuki Sidekick with 160k on a 1.6l;

Runs good about 80% of the time. The other 20% of the time it runs rough and kicks out a cloud of smoke that is sometimes white, sometimes brown. Usual signs of head gasket aren't there. There is no oil in the coolant, no coolant in the oil, and no bubbles in the radiator. The car runs cool and doesn't lose coolant, even though there appears to be moisture in the smoke as well as oil droplets. The motor shakes and clatters during these smoking spells.

Then, as quickly as it started, the symptoms disappear and the engine idles smoothly with no smoke. (Fuel consumption appears really high for an import 4-banger; about 10 mpg but then we are not sure that the gauge is working since we just got the car).

Is this a case of a malfunctioning cold start system or electronic fuel control module? Doesn't matter if the engine is hot or cold--symptoms pop up for 10 minutes or more, then disappear. Choke malfunction (is there a choke?)? Brain box bad?

Also; maybe my imagination but the oil is overfilled by a half quart and has the slight smell of gasoline to it.

--Ernie