Preliminary Inspection

Check all vacuum hoses for correct routing, restrictions, cuts or other damage. Inspect difficult-to-see vacuum hoses beneath air cleaner assembly and other engine components.
Inspect all engine compartment wiring for proper connections. Also check wires for pinched or chafed spots, as well as contact with sharp edges or exhaust manifolds.
The preliminary inspection is very important and should be performed carefully and thoroughly, as it can often fix a problem without requiring further diagnosis.