I have a manual by the way

I was at a stop and the rpms were going up and down at a constant and precise pace between 500 and 1000 rpms???

 

thats been happening to me too i duno wat it is. i thought it was my tps sensor but it wasnt that nor the throtle body... when i shut the car off and turn it on again it seems to fix it cus when that happns u get realy jurky shifts.... its realy anoyin. does any one know wat else it might be????

 

Clean and adjust your FITV and IACV...do a quick search, there are lots of posts about how to do it.