Head gaskets on the way out?

Lately when i start up my car after it sits for at least half an hour, it will idle low and start to miss and struggle slightly, then pick up, let out some white smoke, then run fine, allthough it smells like it is running rich. Figuring my fuel was probably turned up, i took it in to my mechanic to have it adjusted, but he said that if it was rich, i'd be seeing black smoke, not white. Says that there is probably a headgasket going out on me and it's letting coolant get into the cylinders slowly, then it collects while sitting, causing it to smoke and run weird on startup. It also gets hot if it idles for a period of time like sitting in a drive-thru. Any opinions? I paid about $700 for the car, so if the headgasket blows, i'll probably just buy another car, seeing as this old v6 isn't really worth the expense and trouble with the mileage it's at now(190,000).

sounds like a good possibility

Sounds more like a intake leak to me.