I have a '98 Z Auto. When the car warms up I get a very rough Idle. It is also rough after I've been driving the car and pull up to a stop light. Sometimes I have to give it a little gas to prevent the car from stalling. The RPM's bounce anywhere from almost stalling to 1100. I've changed the Fuel Filter and Spark plugs too. I've even sprayed my throttle body several times. I just can't seem to figure out what is wrong. The problem is only at idle. Thanks.

Is your check engine light on?

No check engine light. Hasn't thrown any codes. So I'm not sure what the problem is. Any Suggestions?

Could be a lot of problems, but it is usually your O2 sensor. Check your gas mileage, if your are using a lot of gas this is usually the first suspect. There should be many posts on this site with regard to testing and changing your O2 sensor.

Thanks a lot. I'll check them out.

my car was doing that, it turned out to be the ignition coils, or one of them...

dose it fell like you hitting the rev limiter some times other then at top rev if so look at your inj modual posabull coil