Engine running lean on one side.

[BlueOval Ralph]

a leak in the headers or collector?

Originally Posted by Adger Smith

Switch the leads and the sensors. Verify it isn't the way y
ou are reading it. Like Rich said.... Pull the plugs and verify it is lean. If you went up that many jets the reading should have changed. I would say something in the data system is subject if the plugs look ok. If it is reading correctly and still showing lean then there might be a fuel supply problem. Increasing 6 jets if a fair amount of change.