1965 Buick 300 Help

I have a 1965 Buick Skylark with the 300 and 2 bbl rochester carb. I was driving it yesterday afternoon and drove it for about an hour. I came home put it in park and turned the key to shut it off. It compressed the pistons another stroke and shut off kind of rough. I opened the hood and noticed a small amount of white smoke coming from the fuel filler cap. Didnt think much of it considering it was hot out and I had driven it somewhat hard. I went to start the car again and it started just fine but the white smoke continued from the oil filler cap. I went inside and let the engine cool. I went to start it today and noticed that it would start but it kept shutting off and wouldnt hold idle. After about 6 tries of it shutting off and me feathering the gas to keep it running it finally held idle. I reopened the hood and noticed the same white smoke coming from the oil filler cap but it doesnt appear to have lost power. Engine rebuild? PCV valve? Intake gasket? Piston rings? I dont know. Help please.
 
Back
Top