id almost bet 100 bucks that u have a vaccum leak. My T boot connection that goes on the intake right under the supercharger snout was disconnected and i had the same problem with boost indicator. If the leak gets bad enough it will throw a throttle position sensor code. Anyways there is like 4 or 5 vac lines if im not mistaken. just trace them all out and look for leaks or even completely disconnected lines.