Can't get manifold off..

I'm sure you have, but got to ask. You did remove the valve covers? As they can keep it the intake from coming up. I've had many valve covers that can refuse to come off. If you can find a corner of the intake that you can start a flat putty knife or chisel to start driving under it, it should pop up for you. Just be sure to get it under an area that won't affect the sealing ability. And like cannucky said. Get the silicone cut out.