Kening

my car's [1993 (GLE)altima] idle was good as long as it was cool. Later (about 30m) the idle will suddenly drop .It will idle around 500 dip a little then go up to about 800.Any help would be great.

JustSayGo

Read about idle control system. Look for obvios vacuum leaks and then check the IAC/ACC solenoid by unplugging the wire connector plug when the engine won't idle right. Heat is probably causing the solenoid to hang-up. It would be likely that with the hood open the temperature will cool enough around the solenoid that the engine will idle correctly making the problem difficult to diagnose.

KIKIN

WHEN DOING THAT TAP ON THE MAF SENSOR IF THE IDLE SPEED GOES TO NORMAL THAT MUST BE IT.YOU NEED TO CHANGE THE MAF SENSOR.http://www.autozone.com/servlet/UiBr...3d801b61fa.jsp