Originally Posted by honura
Sounds to me like a sensor or a vac is no good . Take a look at everything and make sure all vacs are hooked up . Do you get a CEL ? If so what are the codes ?
True, sometimes the secondary O2 sensor will be giving bad readings, consequently the ECU will be adjusting the air/fuel ratio. So if the O2 sensor is constantly giving incorrect readings, that would cause your idle to increase and decrease w/o warning.
Check for cracked or broken vaccum lines. That has most often been the source of my problems in the past.
Good luck :thumbup: