I have a slightly rough idle when in gear, a little bumpy, that is also evident in park, but not to the same extent...

When I say slight, I mean slight...I'd wager that if someone else took it for a drive they wouldn't notice, but since I've had this D2 for so long I'm well attuned to any changes...call it Land Rover Nervosa...

So far I've changed plugs and wires - STI 8mm and Champion Double Plats (old plugs looked perfectly fine btw), new air filter, cleaned out the throttle body 2x, cleaned the crap out of the IACV (no more extended buzzing noise from it after shutting car off, yay!)...I have absolutely no leaks (very **** about maintenance and can't go for more than a couple of days with leaks)...

I also ran a bottle of Redline Fuel System Cleaner through the tank a few hundred miles ago...

Where do I look next?

EDIT - just to add that it runs smooth as silk once I hit the gas...no hesitations, nothing, and runs like the day I bought it...

 

Sounds like the same issue I'm having. I noticed an improvement when I put an OEM Mann air filter but it still doesn't idle as smooth as my '99 D2 did. I'm going to swap out the Bosch platinum plugs the PO installed and put in OE non-plat plugs set to the OE gap. Even though the head gaskets were replaced and the heads rebuilt the shop didn't clean the throttle body so they probably didn't clean the tops of the pistons while the heads were off so I may do a SeaFoam hot soak this weekend before I do the spark plugs.

 

Try cleaning out your PCV hoses...I was amazed the amount of crap that came out when I cleaned mine out. Just pop off, and blow or flush the crap out of the hoses.

 

Every Disco I've had the pleasure of driving had a rough idle. How rough are we talking? I admit it shouldn't be "Jurassic Park here comes a T-Rex cupholder rough" but...

 

Not meaning to get too far off original topic, but what exactly a Seafoam hot soak? Is that different than a regular induction cleaning with Seafoam, or just a sexier name?

 

I did one today actually... and left a nice sexy smoke screen through the neighborhood!

 

I have the same issue. It feels almost as if the truck "skips" every 3-5 seconds without throwing any codes. I cleaned the PCV hoses and separator while doing the head gaskets -- unlikely thats the issue (if there is one). As long as there aren't codes I wouldn't be too worried. But if someone figures out what it could be I'm all for smoothing it out.

 

I call it a hot soak because thats what I was told it was called and because you are soaking a hot engine with cleaner.

The way I was shown to do a hot soak is once the vehicle at running temp continue to drive it for at least 20 min so everything in the engine is fully up to temp. Then do your top end/intake cleaning/hot soak with the chemical of your choice, I use SeaFoam since its the easiest to get but have had good results with Swepco 503 fuel treatment as a hot soak chemical. Now once you have ran the amount of chemical you want through the intake system turn the engine off and let it sit as long as possible, preferably over night.

 

Check your fan blades and make sure nothing is missing. Otherwise I never was able to get a completely smooth idle and just accepted that tiny bit of roughness. No one else seemed to notice though.

 

Sure it might be nothing and just something we're all going to deal with but Yikes......

"...As long as there aren't codes, I wouldn't be too worried..."

Why would you suggest he not even try cleaning his PCV hoses out? It certainly is not going to hurt anything?