13bpower

I have a 88 convertable, non-turbo. I just ported and polished my intake manifold today. I put everything back together, being very sure to put everything on and in the right spot, and now i have a problem.
When I turn the key it starts up fine. The engine revs to about 4k by it self and then jumps down to idle and dies. If I stay on the gas pedal i can keep it going. It sounds like it is running rich because of backfiring. I am fairly certin I got all the vaccum hoses back in the right spots. What could be causing this? Please help!!!