my 92 idles around 700 when its warmed up. yet im not so sure how accurate the gauge is under 1000. the vibration at idle can be weak motor mounts or egr valve ports are clogged. mine is an automatic, it has always vibrated at idle. ive had my front mount replaced. that took care of an obvious vibration in reverse. mine doesnt chug. i did have a valve that was out of adjustment that made the car run rough.