2004 Monte Carlo SS. She runs fine if you keep it below 2200 rpm. Shifts fine. But when you try to accelerate past that point she just goes to spitting and sputtering. I’ve changed spark plugs, injectors, coil packs, and a new fuel filter. She does idle about 1200 rpm….HELP!

Plugged exhaust? Fuel pressure under load?

Moved from the "General GM Chat" forum to the "Chevrolet" forum.

I don’t think the exhaust is plugged. Check engine code read a running rich mixture. And a Evap code? I’m guessing the fuel pressure would have to be tested??

Seems like unmetered air is getting in, then when you try to open it up it can't keep from running too lean.

I’ve checked all the vacuum lines they are good.

That'* a good point: What codes are stored?

Also, have you checked the air filter to make sure it'* still fairly clean?

It has a K&N air filter on and NO I haven’t checked it. I’m gonna double check the codes this afternoon.

Blegh!

I know opinions vary, but I am not a fan of K&N. If yours hasn't been cleaned, oiled, and maintained properly then all kinds of shenanigans can happen.

Looking forward to what you find . . .