Ok..maybe thats a bit too vague..here's some links to explain further.. The 1st link below explains how a manometer works. read through it. Figure 2-1, 2-2 and 2-3 are what i'm talking about. Each end of the manometer ties into one one respective side of your throttle bodies. If your throttle bodies are out of sync one side will move up with respect to the other side. This means that one side is pulling more vacuum than the other. There is an adjuster screw you can reach to sync the throttle bodies. It can be seen easily if you are looking behind the oil cooler with your head on the ground looking up.
Before you do any of this work you have to close the open idle bleeder screws located on each throttle body.
Second link shows you what a cheap manometer looks like: You can see the two ends that connect to each respective throttle body.
If all this sounds confusing, take some time to throughly do some research before you jump into this.. its easy to do if you are well informed... I'll post some DML threads on it for you later.
Remember whatever fluid you use DONT LET IT GET SO HIGH THAT IT GETS SUCKED IN TO THE ENGINE. THAT WOULD BE CATASTROPIC