Does anyone know how to slow down the blow by on my '96 12 valve? It puts out quite a bit of smoke from the tube underneath

 

If you try to slow down the blowby it will build pressure inside the engine until a gasket or seal blows out.
If the blowby is excessive you need to find out what's causing it.
Could be as simple as a vacuum system leak or as bad as an engine that is worn out and needs rebuilding.