Rough idle(200-300RPM)off idle runs great no white smoke

Worn valve guides allow oil to drain into the cylinders, causes blue smoke, fouled plugs will idle rough.
Coolant in the cylinders from a blown head gasket will cause white smoke.

If the problem is not a vac leak, it could be the idle circuit inside the carb. You may have to replace or rebuild the carb to fix it.

oooooooooooo my friend white smoke mens head gasket is gon sorry

If you are sure it is white smoke and the car overheats or looses water,The head gasket is bad.
Or It's valve seals or rings smokes (but the smoke would have a blueish tint)

Thats usually a bad symptom. Burnt valve. Do you see white smoke when you first start the car in the morning? If so valve guides and and valves need work. I just went through it with my car. I removed the head and had it overhauled 2 hundred bucks. and now it runs great. Good luck P.S if you have a shop do it it will be 14 hundred.

coolant temperature sensor boken, check and replace if defective.

Not saying this for sure, but I had the same problem, and i have a 1994 xr7 V6 3.8 L , and all u need to do is set the idle down manually because your computer could have seen that the injector was stuck open, and tried to turn up idle to keep up with the amount of fuel being pumped, worth a shot :P

white smoke is antifreeze try checking the compression

I had the same problem on a Rover. There was a leak in inlet manifold that was caussing the problem.
To verify, spray some sealant to temporarily seal the inlet manifold .and the eratic idling should disappear for some time.
If it does, you know there is leak in inlet manifold which you can take of and refit with a new gasket.

Check your idle control valve. You might have to replace it, 80-90 bucks new. Or see if there is an air leak from the intake manifold. had the same problem.