rough idle. help.

[jd daewoo]

My 2000 lanos runs smooth until I put it in gear. It seems to act as if it is starved for gas. Turn the a/c on and it nearly dies. My mother in law drove it the other day and said it was smoking (white but she wasn't sure if it had a blue tint or not tho). I haven't seen it smoke but fluids seem good. Any idea? BTW, I rebuilt this engine a year and a half ago. New valves, seals, head gasket, valve cover gasket, timing belt, fuel pump, water pump. Thanks in advance.