The manual CRVs have a shorter geared transmission like a sports car. So 5th gear isn't a powerless overdrive gear it is another power gear. This helps city fuel economy a bit since I can be in 5th around 40 mph easily. My GSR Integra had over 200,000 miles, did 4k at 80mph and reved to 8k through VTEC regularly. Honda engines are rev happy and you shouldn't worry about holding rpm at 4k or even higher but the CRV gets poor fuel economy the faster you go with wind drag. As far as your misfire goes, if you're not getting a check engine light then your plugs are probably worn out. My Civic puttered at idle and eventual threw a code but I just replaced plugs and it was golden.