How do you find vacuum leak on a 91 pontiac grand am?

How do you find a vacuum leak?

• My car has rough idling, when I'm on [D] but stopped somewhere, the engine shakes. I notice my mileage has been very low since this started and acceleration is slower then usual.... I was told on here, I have a vacuum leak. Is there any way i Can find the leak or do i need to take it to some Auto shop? 2nd question: When I'm on a smooth road driving between 40-75mph., The left front wheel vibrates and makes a low rumbling noise. When I step on my brakes, sometimes the pedal sinks to the floor before working and feels like it skips on the rotor. Would a problem with my brake system cause these symptoms? '00 Ford Contour Front wheel drive.

• Answer:

  Not to dis Dave but I think the engine will actually change speed if you've found the vacuum leak with the carb cleaner not necessarily shut down. The front wheel vibration seems to be more than one problem. Your pedal going to the floor indicates either a low fluid level or a leak somewhere in the system. Brake fluid leaking onto the rotor could cause the feeling of the pads skipping and that would relate back to the soft pedal. Neither of those issues is likely to cause a vibration however. Assuming you had the brake pads and calipers checked when you did the work on that wheel I'd suspect that the vibration may have more to do with your tire, wheel or alignment. Or... the replacement of the parts wasn't done correctly.