vacuum leaks aren't the easiest, but if you pick up some carb cleaner and CAREFULLY spray it around where you think it may be leaking and your car rpms spike a touch, there's your answer.
Similarily if you're REALLY seriously considering a vacc leak, you can take the car to a place that has a smoke machine that will pressurize the system and smoke will come out of the place of the leak. If you're cheap like I am, you can also make one out of a pvc pipe blocker tapped with an input threaded into it, a very low psi (like 3-5psi) regulated air stream from a compressor (CAREFULLY), put some air into it, and spray a water/soap mixture all over the place and watch for bubbles.
Similarily if you're REALLY seriously considering a vacc leak, you can take the car to a place that has a smoke machine that will pressurize the system and smoke will come out of the place of the leak. If you're cheap like I am, you can also make one out of a pvc pipe blocker tapped with an input threaded into it, a very low psi (like 3-5psi) regulated air stream from a compressor (CAREFULLY), put some air into it, and spray a water/soap mixture all over the place and watch for bubbles.