For clarification did it start doing this the first time you started it after installing all you upgrades or did it run fine for a while and then start not idling?
If the latter I would also guess wiring - check all connections and make sure they are solid it is also possible that the ignition system is going bad.
If it didn't run correctly right after your install then I would first check the plug for excessive oil residue (improper fuel/oil mix) and make sure you properly torqued down all the bolts for anything you took off. Properly gap you spark plug it maybe the DR kit needs more or less gap, I would ask around for that info. Good luck