i think that i have my gauge hose attatched to the wrong vac line... i have it going into the line right before the cruise control main. i am getting a 20-23 reading at idle and i give it gas and it barely moves but i brake or turn on my cruise and it will actually fluctuate can any one tell me what line it actually goes into please

 

I haven't hooked one up on a Neon, or seen one installed on one. I'd say you have a few choices looking at the vacuum diagram. There is a vacuum line coming off of the throttle body to the purge solenoid and a line from the intake manifold to the air cleaner (I'd try this one first. Manifolds are generally the place to find vacuum readings). There is also the brake booster if all else fails.