Small vacuum lines to air cleaner of carburated 2.0 liter Honda

Here's a link to your vacuum lines. Repair Guides Component Locations 2 5l qr25de I4 Engine AutoZone com

FOR A 2.4 LITER ENGINE
Air Cleaner Element Inspection/Replacement

1. Remove the air cleaner bolts (A) and the Air cleaner Housing cover (B).
2. Remove the air cleaner element (C) from the Air cleaner Housing (D).
3. Check the air cleaner element for damage or clogging. If there is damage or clogging, replace the air cleaner element. Do not use compressed air to clean the air cleaner element.
4. Clean and remove any debris from inside the Air Cleaner housing.
5. Install the parts in the reverse order of removal.
6. Good luck
   

Rough Idle usually indicates a vacuum leak. You may have to feel along the lines that are routed in the back. My expedition has a small line that is routed from the PCV valve to the back of the intake where it goes from a small hard vacuum in to a reducer connection. This connection crumbled. The vacuum lines deteriorate over time. Some may not look bad, however they are like a sponge. sucking air the entire length.
I use a propane torch (not lit). Turn on the valve and trace the vacuum circuit. If you have a leak, the engine will rev up slightly when the torch passes the leak.

Your 1989 cavalier is a 2 liter fuel injected engine so yes you do have a computer to run the engine so check your fuses and start with the simple and replace the fuel filter, air filter and clean the throttle body with throttle body cleaner. Don't use carburetor cleaner, the carburetor cleaner is to corrosive for the gaskets used in the throttle body. Also make sure all the vacuum lines are connected and not damaged, a bad vacuum line to the MAP sensor will cause what your having.
Good luck and keep us posted. Be glad to help you get your car running 100% again without the cost of a garage trying to be like the tax man.
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Timing belt not adjusted correctly, loose or incorrect vacuum lines, missed an electric connection somewhere, Vacuum leak on intake side somewhere. Sparkplug wiring incorrect.

definitely a vacuum leak. do a visual inspection to make sure all of the vacuum lines are connected. if possible, use a service manual to make sure they are all in the right places. make sure the intake manifold bolts are tight, as well as the throttle body/carburetor bolts. an easy way to check for vacuum leaks is to use a can of carburetor cleaner. DO NOT DO THIS WHEN THE ENGINE IS HOT!! let the engine idle, and pray the carb cleaner around the vacuum lines and fittings. if you spray a leak, you will hear the idle go up very suddenly, or it may start to stumble and try dying. but it will be very noticeable when you do find the leak with this method.

everywhere on the engine intake area, use a can of carburator cleaner and spray around the top of the engine, u will hear a change in the engine sound and idle speed when u hit a vacuum leak.

Check pcv valve and vacuum hose to make sure they are working. Chances are that you have a broken or worn ring, or worn engine bearings. (excessive blowby) In which case there's not much short of rebuild or replacement of engine that will cure problem. You could remove the hose that is bringing the oil into the air intake off the air cleaner and route a longer hose into a can or something temporarily but it's not a cure.

make sure the idler motor is conected and wires are free and not stuck under the intake, and also check the pcv valve lines for proper routing, also check the line going to the vacium booster for brakes, and one of the ways to find vacium leaks is by aplying brake or carburetor cleaner to the suspected area and that will change rpm when leak found