Several things may cause a rough idle on the 2002 Chevy Tahoe, but the most common is in the tune up. Depending on which ignition system you have -- the standard distributor, or the distributorless (coil-on-plug) system -- the tune up could take less than an hour or a few hours. The engine light may or may not be on, depending on how "off" the air-to-fuel mixture is due to a prior (and poor) tune up.
Remove the plugs from their boxes and lay them out on the front of the vehicle. Pull the plug wire off the first plug.
Remove the plug, using the spark plug socket. Insert the new plug and screw it in by hand as far as it will go.
Tighten it firmly with the spark plug socket. Reattach the wire. Replace the rest of the plugs in the same manner.
Pull the plug wire off the first coil pack. Unplug the wiring harness connector for the coil pack.
Remove the ignition coil, using the appropriate socket. Remove the spark plug, using the spark plug socket. Insert the new plug and screw it in by hand as far as it will go. Tighten it firmly, using the spark plug socket.
Reinstall the ignition coil. Plug in its wiring harness connector. Reattach the plug wire. Repeat for the rest of the plugs and coils.
