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A few things to check:
(1) make sure you did not loosen or tear the air intake duct between the air meter and the throttle body; any unmetered air entering at this poiint would cause the symptom you describe.
(2) Check thoroughly for any disconnected, damaged, or leaking vacuum hoses.
(3) make sure the idle air control plug is not loose or disconnected.
(4) Check the EGR valve to verify that it is not stuck open at idle. Ditto for the airflow meter plug.
I hope this is helpful; if so, clicking my accept button would be most appreciated.... thanks!