'91 754T Intermittently have had puffs of smoke that then disappeared. Looked white. Recently noticed that upon start up it smoked some, then at warm temps seemed to stop. This evening, I noticed that it was smoking trememdously upon idling, seemed to thin out when running, but when I would take foot off gas pedal would smoke up pretty good. The smoke keeps coming out even after car is turned off, until it is all out of exhaust system. It does not smell like typical burnt oil, however I am using a full synthetic oil. Would this make it smell different? It reminds me more of what a friends overheated Cat. Converter smelled like rather than burnt oil. HELP Need suggestions about first thing/way to check as soon as possible. I tried to look through FAQ but did not see anything like this (could have overlooked it though haha).