so when i accelerate above 3,000 rpm it does this weird studdering thing where it shudders and still accelerates but has a hard time... does anyone have any idea what this could be or what could be causeing it?
thanks

 

i had the same problem it was my fuel pump. but check the pressure tho and check cat convert cuz mine ended up bad also clean injectors and intake and egr valve. mine was also clogged from a bad cat which helped ruin all of this cuz fuel pump was pumping to much gas cuz egr was faulty which led to bad cat and clogged evrything. also i had a bad coil so only 4 or 5 plugs were giving spark to spark plugs which made it run rich and helped ruin cat faster

 

I didnt see this thread and posted almost the same thing. What should the fuel pressure be? Mine does it when it kicks down into the passing gear or on hard acceleration I guess you could say.

 

i have no idea what the ideal psi is. but im gonna try and replace the fuel pump and see if that fixes it. as well as check the plugs to see if any of them are fouled.
i have noticed that it doesnt do it all the time. i get lucky and every now and then when i drive it (not hard) it will drive just fine.

 

Mine was doing almost exactly what you describe. I put in new spark plugs and wires, and it's now cured! The Haynes manual says that the spark plugs and wires on the 3.4L engines are supposed to be changed every 30,000 miles, as opposed to every 100,000 miles on the 3.8L engines. Based on this, I'd bet that a lot of people with the 3.4L engines don't change their spark plugs and wires as often as they should.

 

the pressure is supposed to be 45 when not running but when idling it should be at 35. like said before i hade the seam problem a coil was bad and cat convert was plugged and it helped cause my spark plugs to fail quickly. and 2 wires had to high of a resistance. my first bet is do a tune up change fuel filter 5bucks wires 40bucks and go with ac delco spark plugs 30 bucks so around 80 bucks with tax and i bet it'll run better. if not a tune up is a must and if it doesn't help well it prolly needs it. and then from there check your coils buy pulling 1 plug off at a time hooked up with wire to the coil pack and start engine and check for spark AFTER you do the tune up (furl filter wires and plugs) and go to all 6. and follow the wire to the coil to see what cylinder it is and you might find your coil pack is firing good one one cylinder but bad on the other this means bad coil and replace it about 30 bucks your might have a 2 out of your coil pack only doing a 50 percent of its job. then after that it will prolly be fixed also run sea foam thur fuel tank and in brake booser to help clean injectors and intake valves. or get it done through a motervac system cleaner. if still not fixed it is probably your fuel pump but before that get the fuel pressure check because a pump it 300 bucks.

 

Check for exhaust leaks. It's very common for the manifolds to leak. Also check the EGR tube to the manifold, it could be leaking there too.

Now, the EGR could be bad as well. These cars are notorious for that! How's your fuel mileage? Is the car running rough? Do you have black smoke out of the exhaust when you start it cold? When you have a bad EGR it'll cause the car to sputter too.

 

i allready put new plugs in about 5k miles ago but i was gonna pull them all and see if any were fouled. i will check the wires tomorrow. i know that i have an exhaust leak at the muffler and at the manifold.
my mileage seems fine. but it just anytime when i accelerate harder than 25% it just sputters and goes to ****. so i will try that stuff first. thanks!

 

Check for codes, did you scan it?