Hello there, I have an 03 mazda 6s 3.0, it has almost 150k on it. I have had an issue ever since purchasing it back in 07 that its time to finally address. while in 3rd gear accelerating after slowing down, the motor often studders, (not quite a misfire) until rpm's catch back up over 3000. It makes it hard to drive when it gets warmer, and if the ac is on it does it more often. I'm going to dig into it tomorrow, and am planning on replacing the coil packs, the plenum gaskets, the pcv valve, and the valve cover gaskets as I have an oil leak as well. Is there anything else I should look into? The car has been religiously taken care of as far as service since I got it. Plugs were done about 20k ago. MAF sensor is cleaned every oil change as well. Just want this problem to go away, I dont mind it, but it drives my wife crazy.
Thanks for any suggestions!

Jason

 

Clean the throttle body with throttle body cleaner (not carb cleaner). Change the throttle body gasket. Clean the EGR valve. Glad your changing all the ign coils. Please change all the plugs again, especially if you have oil in the plug area from above. Oil leaking on to plug/coil could cause misfire.
Add a ground wire from the engine block to the negative terminal of the battery. Add another smaller ground from throttle body mount bolt to negative terminal. Check your main body ground as well. Another bad ground area is pic attached.
For more pics on intake plenum: Mazda Forum - Mazda Enthusiast Forums - UseYourNoggin's Album: Intake Plenum & PCV Valve. 2006 Mazda 6 V6 3.0 ltr.

 

Came up with a couple more issues with high mileage 3.0 ltr V6's .

1) replace the OCV seals. You can't buy them at dealer, you need to buy them here: Twisted Visionz - Online Store ------he is the Mazda 6 Guru.
His procedure to install them is: DIY: 3.0L V6 Oil Control Valve Seal Replacement

2) Fuel Injector Seal Replacement: DIY: Fuel injector replacement on 3.0L duratec
A leaky injector seal could be sending too much fuel in to cylinder causing your poor performance on low rpm's.