Engine runs rough. Want it to run smoothly.

[Maleficio]

Originally Posted by F18Rep

OK since nobody has mentioned it and you are maybe running rich....How's your o2 sensor, bad crimps are pretty common. Some of the local motorheads here in the backwoods of Missouri solder/heat shrink them and then with a little chuckle, nick the insulation just in case the "reference air" story is not just bad joke.... Bruce
PS... You think maybe you could get your QA guy to sign off on a repair like this?

I replaced the lambda sensor last summer. I did it right.

But when it's connected, the car can't seem to figure out how it wants to regulate the air/fuel. Its not steady. Idle doesn't lope, but you can hear/feel the explosion dynamic constantly changing. when I disconnect the lambda sensor, the car stabilizes, and runs stronger.

Maybe this is from a mystery vacuum leak?