My girlfriend has an 08 impala ls with the v6. When accelerating it kind of hessitates I guess I could say. You can see the rpms drop a couple 100 then go up. When accelerating hard the check engine light will flash multiple times. I'm guessing its due to misfiring. But the car is not throwing any codes and idles perfect. It will even do it going 65 with the crouse control on. We dont have a lot of money to take it to a shop. I tend to work on my own vehical. Just asking around to see if anyone has any idea what this could be. I'm going to do the plugs and wires soon as possible. Figure that should be done any way seeing the car has 123,xxx.
if you made it to 128k on the original plugs that's impressive. by 105k mine had a miss at 4500 rpms. plugs and wires cured my issue, i'd guess they wouldn't hurt yours since you're due anyways. good first place to start.
on my 2010 3.5 i had to remove the top motor mounts going to the radiator support and roll the motor forward 4 inches to get to the back plugs. the one by the alternator was a pain but do-able.