Hi, I just put a set of heads on a 350 that is all new.
The heads were from a different engine and I know they have been shaved ALOT.
I used a new aluminum intake and am having tuning difficulties, is there any chance that my intake needs to be machined to match my heads, can there be a vacuum leak into the lifter valley ?
When the engine gets hot, it doesn't run as good as when it's cold, And some of my spark plugs are alittle damp with oil.

Thanks !!!!  

If the heads were angle milled there is a very good chance there is a sealing issue at the manifold & cylinder head face, this vacuum leak could be sucking oil into the cylinders from the lifter valley.

A machinist is supposed to correct the intake manifold face on a set of cylinder heads when he angle mills the them so this problem doesn't arise but maybe someone was too cheap or someone (meaning the machinist) didn't do a very good job. If you don't want to take the heads off, have the disassembled, milled, cleaned (again), and re-assemble them you may be able to have a machinist correct the face of the intake manifold by milling it but then this manifold may not bolt to another engine that you want to use it on in the future.

If the heads were milled FLAT, this shouldn't be an issue as it doesn't interfere with the intake/exhaust manifold face angle.