Today, I replaced my O2 sensors and swaped my MC platinum plugs for MC copper. Before this, my engine, when cold after ignition, would start and revv at approximtly 1800 for about 15-20 seconds and then rev down to 850-900rpms. Now after replacing those items, after a cold ignition it revvs to approx. 1000 rpms and then lowers to 850. I was under the impression that it was supposed to idle high for a little while then drop to normal. Am I having an issue or did I have an issue that I solved with the 02 replacement? It does run a lot better now though...