I had this problem before but it went away a bit after an oil change and oil filter change. I have a manual so i shift into neutral to coast. But the tachometer only drops down to 1500 or sometimes up to 2500 rpms instead of it's normal 500. I've been told before it was probably the throttle body. I took that off and scoured it clean until it looked brand new. It stopped for a while but now it's back. Any ideas?

 

Also when I accelerate on the road it revs up higher after I let up off the gas and stays in higher rpms for a while before dropping down to 1500 or so.

 

Go to autozone, advance, napa, o'reilly, etc. and have them do a quick OBD-II readout. Write down any codes listed if there are any.

It sounds to me like you may need one or two new sensors (both on the throttle body), the IAC (intake air control) and/or TPS (throttle position sensor). That, or you have a leak in one or more of your vacuum lines. I would give all of them a good check too - especially the ones coming from the charcoal canister.

 

Haven't been to an auto shop yet but I looked up neon codes and I got an all clear there.

 

If you idle is steady around 900 rpms, your IAC is toast. Had this problem. Decided to get the manual IAC from modernperformance, rather than spend $75 on a new sensor, and wait for it to fail.