370z Dumping Fuel into Cylinder 2,4,6.. WHY??!?

Jhill

You wouldn't get any other code but a lean bank code. The system has no way to determine an exhaust leak pulling air in before the A/F sensor. It has to take it on faith that it is sealed and the A/F sensor will be seeing that raw air as a lean condition and then dump fuel. Same thing will happen if the intake gasket on that side is not sealing drawing in fresh air after MAF. The p0300 is a random misfire code, misfiring because it is flooding the cylinder.

From the op description I would be leaning towards a gasket leaking (intake or exhaust, more likely intake just because most cars are much more likely to have an intake leak than exhaust but not all, cracked Honda exhaust manifolds anyone?), the intake is extremely common on Chevy v8 with the ealier gaskets and will do the same thing, get warm enough to go into closed loop and then start dumping fuel possible misfires and then settle out as it gets fully warmed up.