My IROC is running poorly. The battery is shot after storing it all winter, so I'm replacing it with an Optima. It won't go into closed loop and and the O2 sensor goes from 420mv to 460mv. I replaced the O2 sensor and it still reads the same. I also replaced the distributor and the Coil before putting it away for the winter. The car will heat up to normal operating temp. I'm thinking it is the ECU (engine computer), but am I missing something else?