I did not get around to installing all of the silicone hose today, but I did get to install the new O-rings under the intake manifold. I saw evidence of a vacuum leak in the form of stains where I took the old O-rings out -- the edge where the O-rings push in is very sharp and the O-rings had been cut by it. So this time I oiled the O-rings generously before putting them in. Although I didn't get a chance to start the engine, I was also able to install my security system, so I accomplished two things today!