2004 Mazda mpv running rough

2004 MAZDA MPV
125 MILES • 6 CYL • FWD • AUTOMATIC
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BRAKE LIGHT
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I have a 2004 Mazda mpv. The problem I'm having is that the car****** at times. Sometimes when driving and sometimes sitting still like at traffic lights. It has the resemblance of a vacuum problem. It gets worse when ac is turned on. Also when it"s changing gears the tach will rev higher. Has not had a check engine light come on. Any help would be great. Thanks, Chris
Jun 22, 2011 at 2:32 AM
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SIXPACK SUBARU
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This engine is known for coil issues....and they are NOT cheap. Best way to diagnose is by part substitution...ie; replace them with known good coils. Bench testing coils, and/or ignition leads is not a sure-fire way to tell if they are faulty.
Jun 22, 2011 at 11:10 AM
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KHLOW2008
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Have the spark plugs checked as well.

As to the engine revving higher, check the transmission fluid level.
Jun 22, 2011 at 11:46 AM
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BRAKE LIGHT
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Great advice guys. I replaced the ignition coils and so far so good. Removing and replacing plenum assembly was tough but was managable. This seems to have corrected the tach revving higher as well. Thanks Again, Chris
Jul 4, 2011 at 4:33 PM