[nize]

actually, i just re-read your post and noticed you may have already read that old thread.

are you positive that you installed the venturi delete correctly? it sounds like there's a vacuum leak somewhere along those lines.

robm-951 has a great suggestion. you can attach a hand pump to one of the vacuum lines (make sure the leaking ends are clamped!) and try pressurizing it to see if they hold pressure. if it doesn't you've found the problem.