Em199civicsi

Need a bit of help I got a ep3 with a k20z3 now when I get on it really hard after I come to a stop or put it in neutral the rpms will jump to 3000/3500 and drop to 1500rpm and it will keep doing it nonstop now when it's in gear if I let it cost and the rpms hit about 1500rpm it will start pushing the gas its self it seem I hooked it to a code reader and it comes up nothing I let it sit over night and it will do it soon as I come out in the morning and start it up it also has a Throttlebody spacer or something not to sure what it is