Hi
I just bought a 98 NL Concorde with 106,000kms

It runs beautifully.

However, when Idling, in drive or reverse it seems a bit rough , almost a vibration or shudder.
Sometimes more noticeable than other times.

My mechanic sat in it and said I am just being a bit pedantic and he said not to worry about it. He checked the leads and the plugs and gave the car a once-over. He said he looked for all the usual suspects for the NL and couldn't fault the car in general.

The 90 NA i am selling idles smoother than this.

Any ideas on what it might be and estimate on cost?

Harmonic balanacer??

it would most likely be the engine mounts..

There is a rubber insulator, that can spin on the lower side of the mount, check it can spin...if not, mount is U/S

Sounds like its the pass side one too.

Check box mount too.

Car has done 106,400Ks.. is mounts likely?

How much will replacing these set me back?

Update.

I have been told there is no way it would be the engine mounts in a car of that KMs.
So I am now trying to identify it via changing plugs - done - no change

Now leads tomorrow night. Top Gun 8.8mm

If that doesnt work we then look at the coil.

Done new plugs, leads rotor and dissy cap.
No change.

Got the EFI serviced today, made a big difference , he said 2 cylinders were affected.

Still just an ever so slight vibration when idling in Drive or Rev.

But now i think i am being pedantic.