Ever since I have had my car, an 89 Iroc 350, the idle has never been where it was suppose to be, it was always a little high, even after I rebuilt the engine, new IAC and everything, the idle was the same as before. And at the same time I noticed that on long drives my speedo would after a while on the road would stick at 60 mph, I would have to hit my dash to get it to go up to where it was supposed to be.

But this past week my speedo cable broke, and my idle skyrocketed. It didn't matter if the car was hot or cold, in drive it idled at about 1100 and in park like 1800.

Well today I replaced my speedo cable, and do you know what? My car now idles exactly where it is suppose to idle, not to high, and not to low, it is perfect.

I guess it doesn't really make sense to me, any of ya care to explain why the speedo cable has anything to do with idle speed?