Well I got my 99 GT vert a few months back and I just noticed a kind of rough idle. What happens is when I sit idle in neutral, it idles at about 800 RPMS for about 15 seconds then shoots to 1000 RPMs for about 2 seconds and repeats this pattern. Is this a normal idle for a 99GT? It has 30K miles on it. Please let me know. Any help would be appreciated. Thanks!

 

yes thats normal. something kicks in either water pump or cooling fan or something kicks in to cool your engine down so it needs power to run that thing so it revs a lil higher then once it cools engine down it goes back to normal. Its cuz your idling so theirs no air helping you car cool down so I THINK its the cooling fan that kicks in to help cool your car down.

 

thanks man, I appreciate it.

 

Is the A/C or defroster on when this happens? That will cause fluctuations, also