I30 idle up problem

[cunsu]

Dear All,

I have problem with my I30 '98, the problem is the engine cannot stable while idle position ( RPM up / down ) , but if RPM > 1000, the engine running well.

I have cheked by Nissan Service station, and they replaced spark plug, ignition coil and cleaning throttle body, but the problem cannot solved.

Please advise, what's going on with my I30, and how to solved this problem.

Thanks B4