Your AMC Eagle probably has what seems like miles of vacuum lines going everywhere from and to strange and mysterious places. A good number of these are related to the emissions controls of the '80's. One bad line can make your car run terribly. So its best to get hold of a vacuum diagram and some new hose and spend the weekend replacing it all.
Now a word about vacuum diagrams. In a perfect world there would be only 1 diagram -- even 1 per year would be tolerable. However, every year AMC Eagle seems to have a myriad of combinations and permutations -- based on the EPA regs that year, for what state the car was delivered to, engine, transmission, etc. etc. So if you are in desparate need of a vacuum line diagram you will need a TSM for your particular model year and you will also need to know which one will apply to your car.
And your AMC Eagle will also have vacuum lines for the 4WD (except '80), the A/C if you have it, your Power Brakes and Cruise Control (if you have it). All these need to be in good shape too.