Little advice needed.

To clarify, I didn't go over 40 when I took it for the test ride. Now that there's no leak in the intake it's runs smooth. That may be an issue with creating more vaccum, I'm not sure. But when I took it over 40 the 2nd day it seemed like it wasn't hitting the next gear. It wasn't whining or anything. When I took it to about 45-47 and took my foot off the gas it slowed the car considerably.

What's the suggestion on what's needed?