Ok I've had my Catera for over 6 months now, I run Premium in it, and have changed the spark plugs (among numerous other things!). Two problems, One, at Idle sometimes you can feel the vibration of the engine, not a ton but enough to be annoying, sometimes it runs like glass. Problem two, I have noticed that when I do get the vibration the temp is usually 1/8th away from the 3/4 mark on the gauge, but not alaways there when I get a bad idle. Don't know if there is a correlation, but what is the normal operating range of a 97 Catera on temp, and how can I get it to idle like glass always (as I assume it should). One other thing I live in a desert type area at about 2300 ft. When I was up north in cold weather last week at about 4700 ft. I noticed the idle vibration to be rougher (you could feel it more). How do I diagnose this and fix it?
Car currently has 97000miles.

Cateras vibrate when they are cold, mine does it ive heard of others doing it as well. It seems to be normal with the car just being cold. After it warms up a little , it stops and on cold days it does go on for a longer duration. The normal operating temp - gauge wise - is give or take halfway. If its only a slight vibration then there shouldnt be anything to worry about.

I dont mean to be harsh but: if it aint broke, dont fix it


Although ,how rough is the vibration? on a scale of 1-10 (10 being the roughest)

I would say about a 6 or 7 when you can really feel it, but it is so inconsistant that its tought to pinpoint what it is.