its a LS in a hatch and the idle is jumping. theres no CEL, so what else can be the problem of this?

 

probably a vac leak somewhere.

 

try searching first bro. this topic has been covered a million times over! but i will help you out this time these are the things that could cause this


vac leak
bad gasket
cracked manifold
iacv needs to be cleaned
fitv needs to fixed ( there's a thread about this in the faq's)
air trapped inside the coolant lines
chipped ecu could cause this
check the pcv & the tps

there you go! good luck im not sure if i missed anything so if i did oh well. someone else could add on

 

If anything, try seafoaming your car. That got rid of mine.