I've replaced 10 valves on this 2004 aveo after a timing belt break and now I have a rough idle and no error codes show up. Valves were hand lapped and new intake gaskets were installed. Rough idle is persistent and only goes away if I pull the connector on the Oxygen sensor on the exhaust maniflold. With this sensor disconnected, the idle improves. Unplugging any of the connectors to the intake system makes no difference. I've tried putting an unlit propane torch to the intake manifold and I hear no change in idle.
Anybody have any ideas or directions in which to proceed?