check idle speed, my sticker on my engine said 850, also older carburated engines make white smoke while warming up, from normal condensate in the exhaust ,intake, gas from sitting, and alot of fuel additives can cause it. but nothing to be really worried about. you will get more if you dont have a cat. the only other thing that it could also be is a stuck pcv valve dumping exhaust into your intake bogging your engine down. thats about it