Rough idle My 99 Buick LeSabre recently developed a rough idle and the engine light came on. Changed plugs and wires. The car diffently runs better but the rough idle problem still exist and the engine light came back on. Could this be a clogged fuel filter? If so, where is the fuel filter located?

So have the vehicle worked on

You have several issues & know that

Stop using it & have it repaired

Have you checked the coolant level or the fuel pressure regulator?

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If there is no "Check Engine" light try a bottle of good injector cleaner in your gas, or cleaning the throat of your throttle body with a good spray cleaner. If the "Check Engine" light comes on then put it on a code scanner and that will point you in the right direction.

Have a qualified tech do diagnostic's on it !
003 Fuel System Tests Scan Data Tests

From the symptoms of the problem and the precautions you have done i think its time to check the EGR valve.Clean your EGR valve and then put it again. How handy you are in ding this?

As the check engine light is on did you scan for error code which will help you more specific to locate the problem.

Fuel injectors go bad on these engines, you can find re manned ones for 30 bucks. If you have an engine light on get that read. Change your coil/wires/plugs also. Is the lower intake manifold gasket leaking coolant yet? You may want to get that replaced also. Check the TPS too (throttle positioning sensor) those will also cause your engine to act up

Sometimes a rough idle like that is a fuel filter. As you've already done the plugs and wires the fuel filter would be my next bet.

I just had the same problem. Replaced the fuel filter,still crappy idle and no acceleration. I replaced the fump pump along with the wiring harness and the fuel pump screen and my cars purrs like a kitten,has back to normal acceleration and idles better than before. Hope this is some sort of help to you. I did it myself. Total cost, a little over $120. Good luck. By the way, your fuel pump should be pushing out about 65 lbs of pressure. is it ???

The Chilton and Haynes manuals show pics of the spark plug wires in the tune-up section.