Old, cracked, or disconnected vacuum lines can cause vacuum leaks. Inspect all of the vacuum lines under the hood and replace any that are damaged.
Step 2: Clean your carburetor.
A dirty carburetor can cause vacuum leaks and reduce engine performance. Remove the carburetor and clean it with carburetor cleaner.
Step 3: Check the PCV.
A stuck PCV (positive crankcase ventilation) valve can cause vacuum leaks. Check the PCV valve and replace it if it doesn't work.
Step 4: Check your spark plugs.
Worn out or fouled spark plugs can cause vacuum leaks. Remove the spark plugs and replace them if necessary.
Step 5: Check your ignition timing.
Improper ignition timing can cause vacuum leaks. Turn your engine to TDC and verify the timing is correct.
Step 6: Check the valves.
Worn or damaged intake or exhaust valves can cause vacuum leaks. Have your mechanic perform a valve job if necessary.
Step 7: Check the camshaft.
A worn camshaft can cause vacuum leaks. Have your mechanic inspect the camshaft and replace it if necessary.
