hi I'm looking to buy a 98 z28 camaro, but it has a problem: when I start the engine it revs by itself around 3000 rpm continiously. Can anyone give me an advice?

 

Might be either a bad throttle position sensor or a vaccuum leak somewhere. Don't buy it if you aren't mechanically inclined or don't feel like chasing that problem down. See if the seller can bring it to Autozone or somewhere they will scan the car for codes for free to see what it is.

 

He's probably selling it because it has some problems, and if so, I hope its cheap. If you're mechanically inclined, you could potentially get a good deal, if not, look elsewhere.

 

my car would sometimes randomly idle at 1700, then go back down to normal ( about 700) it turned out that my problem was my alternator

 

It could the alternator they told me after they changed the alternator belt the problem started. The price is about 5000usd