I see no one has addressed your request for guidance yet--so I'll make an attempt to give you some pointers. The fuel injection system in the '79 is called K-jet and is totally dependent on there not being vacuum leaks. You can easily check a few things with a water spritzer bottle. Areas to check with the motor running --
1. around the connection between the intake manifold and the cylinder head (intake manifold gasket)
2. each injector (there are two rubber "O" rings for each) has one skinny ring around the plastic injector holder--and one inside (small fat ring) between the injector and holder. Spray a liberal amount around each injector. These seals dry out and can shrink or crack with age.
3. the rubber upside down "funnel" connecting up to the intake manifold can crack or become dislodged at either end.
4. Any of the small vacuum hoses for the ignition distributor and other components can be suspect.
There are many possibilities as a cause for rough idle but the vacuum check will be a first step in hunting down the problem. Start there and report back. -- Dave