Fuel System Issues?

[Firelancer]

Hello there!

I have an Aveo 2005 four door, and have for a little over two years. It has about 125,000 miles and has a few issues, but overall is a great little car. I'd really like to keep it for several more years.

Recently, though, I've been having issues with it. When stopped at lights or stop signs, it has what I can best describe as a "hiccup" when I'm listening to the engine, and feeling the vibrations through the floorboard. Where it will seem like everything stops - except some whirring - for a split second.

It's also hesitating when accelerating, and the codes have been reading that the pistons are misfiring periodically. It doesn't seem to be the transmission, as it's shifting fine otherwise, and where it always has. We also checked the vacuum lines for any leaks, and there weren't any.

It's also been hesitating around turns and on occasion up hills.

We think it's the fuel system, but aren't sure. Has anyone encountered this issue or have any thoughts?

Thank you!