I recently purchased a 1997 ranger w/v-6. It has a very fast idle when it starts up and wont come down to normal idle speed it goes to about 4000 rpm when you first start it and drops to around 2500 when it runs for a minute or two. When driving it idle at 30mph on a flat road. At a traffic light it has a rough idle and a miss. It has the check engine light on and the following codes were present O2 sensor, 0113 high temp air intake, 1443 emission control or purge vavle. I was wondering where to start if they might all be related and fixing one might take care of more than one. It does have a locking gas cap which I will relace tomorrow with regular one. Any help would be great. Thanks from Florida.