I bought 00 RL with an off idle miss that occurs at about 1500 rpm and goes away in higher rpm's and an intermittent idle surge. When started cold the idle is steady but after warming up it will either go to 2000 rpm (in Park or Neutral) or fluctuate between 900 rpm and 1500 rpm. When it goes to 2000 rpm if you depress the gas pedal then it will normally fluctuate also. A few times it will idle normal but normally it is one of the above scenarios.
A local mechanic thought it needs an IAC for the idle surge (pulled codes) but said the off idle miss could be related or because of valve train out of adjustment or related to a lean code on both banks of cylinders. He replaced the fuel filter (clogged) and replaced all the plugs and told me to run 2 full tanks of fuel with inj cleaner through to see if it improves.

Any ideas?

Thanks

 

I'm not quite get your problem, but do you experience the RPM slighly goes up and down while idling? My RL did that, the RPM goes up and down it wasn't stable and it wanted to die. If you have the same symptom like me, then check the following. The solution was simple(in my case), there is a little tube on the passenger side on top of the ignition coil, one end connects to a module I believe and the other end does not connect to anything. That tube was cracked and I guess it allow air into the system, I just replaced tube and the RPM was back to normal again Hope thats help.

 

Thanks another mechanic who didn't see my car can say my problems can be caused by a intake air leak somewhere. I will check when the snow clears up around here.

 

if those dont work, check your main relay...