Hey guys I have a 01 civic and ive searched and found something similar but does not answer all my questions.

When my car is at Idle it idles at about 8-900 rpms. But sometimes it drops to about almost zero and the car starts to shake and then it goes back up to normal. Ive sprayed down the throttle body and it is a little better but it is still doing it.

And if i try to accelerate smoothly sometimes it feels like it lags or something and it does not really go till i really get the rpm up.

Also sometimes when i come to a stop the rpms stop at about 1100 - 1000 stay there for a second or two and then drop back to normal.

Dont know if this is related to this or not, but i average about 22-25 mpg in the city and i shift at about 3500 rpms. I hope that is not too high.

Any suggestions on what this could be?
PS. Ive changed the plugs already and also the air filter.

Thank Guys