every two years or 30,000 miles？
step 1 Replace the fuel filter. If you have a fuel-injection system,
regular cleaning isn't necessary unless the injectors are clogged.
Step 2Change the spark plugs (unless they're platinum, in which case you
have 30,000 more miles to go). Also examine the spark plug wires and replace
as needed. A new set of high-quality wires is worth the cost. They may be
permanently attached to the distributor cap, so it will have to be changed