Wife got home tonight and tells me our new purchase was being naughty today

At idle the revs are surging and dropping, and under load its running like a bag of spanners. She stopped, switched it off, and back on, and it was fine.
I don't have iid tool yet, so no idea of fault codes.

Anything jump out at any of you as to what it might be? Where I can start looking?

Car has RAC warranty, but I want to have a good idea of possibilities before a garage I don't know just clear the fault codes and give it back to us hoping the warranty runs out before it breaks again (bad experience recently with our Defender!)

I have had similar on occasion. I had a slight misfire at idle yesterday morning from a cold start. Would suspect ignition coil on mine, it cleared within a few seconds of the car just idling and has not reappeared since.

Interested to find out what is wrong with yours though.

good luck Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

I'm going to give a shot in the dark and say air leak, possibly a vacuum hose.

Have a look around at all your hoses, pipes and clips and look for any signs or cracking or splits.

Wouldn't have thought an air leak would stop by turning the car on and off. Idle would probably be higher than normal as well all the time.

cheers Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

MAFF

So we had RAC out three times in last 36 hours. First 2 times it's thrown up air temp and air mass faults (MAF), so we got a replacement locally. It didn't help, and lit engine management light. RAC came out again, and faults code was Running lean bank 2, so it's being trucked 280 miles home. My suspicion now is injector.
Last RAC guy was excellent, checked every pipe and joint for leaks, and really seemed to know what he was talking about.

Pretty good going for 7 days ownership!

Useless contribution! Sorry.  Bish.

2005 110 TD5 CSW
2011 TDV8 Vogue SE (gone)

No contribution is useless right now. Seriously considering sending the car back for a refund right now

If it were the MAF, then disconnecting it and running it would tell you if the MAF was faulty if the car ran better.

Could be an O2 sensor for example if running lean on one bank, but that's a stab in the dark.

You mention air temperature fault, what does the outside air temperature display show?

cheers Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

Disconnecting the MAF just stalls the engine.

The MAF contains 2 sensors - air flow and inlet air temp, so a faulty MAF can throw up both faults.

A faulty O2 sensor could spuriously bring up a Lean fault on one bank, but at the roadside it's simply not worth the risk of running it lean and doing serious damage.

It's now gone in to an RAC approved garage (they insisted, it's an RAC warranty), so we'll see what they say.

My best guess is the car was running in "reduced performance" mode when your wife originally got home , and that's why it was idling badly .

What caused it could be many things , worst being a bad cat (which is also the best as they're free up to 10 years or 85k) )
Best being a bad hose (easily found with a smoke test )

Plugs , coils , mafs , lambdas , supercharged pumps , dirty throttles are also common things that can cause it .

As is a bad battery .
Even if it appears good .....