my sister in laws 626 has a very rough idle. the rpms stay just under 950, with some wavering. when put into gear, it will sometimes stall. if gas is applied it will stay running. reving above 2k the engine sounds ok, but under that there is some knocking that sounds like its coming from the valvetrain. except for that knocking sound, i feel that the mass air flow sensor is to blame. i disconnected the MAF and the idle changed some but was still very rough(on my volvo disconnecting a bad MAF allowed the car to idle good, but it couldnt be revved above 1600rpms,this meant for sure that the MAF was bad) and i was still
able to raise the rpms.
she needs help, im afraid that if she takes the car to the garages close by they will see her coming and replace a bunch of perfectly good sensors.
any ideas you have of things i could check, or your opinons if it could still be the MAF
p.s. i also tried disconnecting the air inlet temp sensor, this had know effect.

 

Do a tuneup that might be your problem. I had a similar problem not too long ago . I replaced the spark plugs ,fuel filters,andin my case a new MAF.