1997 V70r really rough idle and surge on startup

[Luxobarge]

Yep that's what we meant by "check the vacuum hoses" You need to fix both of those issues and any others you find, whether they are directly causing your problem or not. I'd strongly recommend replacing all those small bore pipes, if one is perished then the other's won't be far off. The diagram posted by ElPadrino above gives you the routing for the TCV pipes.

[richmac]

That's good news. The elbow you replaced was the only one Volvo coulldn't find for me so I ended up using a pre-bent silicone tube for it.

In you TCV picture and with reference to the diagram above:

The TCV clips onto the back of the airbox. There's a slot for it that's quite hard to see.

The missing line is the Blue. This goes to the nipple on the fat plastic air intake hose from the airbox to the turbo. It's the TCV's personal 'dump valve'.

The broken top line is the Red. This goes to the turbo pressure output nipple. Follow the line as it's the most awkward one to get to. You have to reach under other bits to get to it. Be aware that it will have a 'squeeze' clamp on it. The line will also be stuck to the nipple so may need pliers to get it off unless you're lucky. Removing the air intake tube makes it easier.

The right angle line is the Yellow. This goes to the wastegate nipple. This is easy to replace if broken but is probably also stuck on by now.

From memory, these are all 4mm internal diameter but 5mm may work (I believe OEM fit was 4.5mm).

There is also a narrower (3mm) line that goes to the manifold (near the line you fxed) from the engine side of the turbo which is the bypass (dump) valve outlet. Worth checking.

As before, these didn't cause the problem but will affect performance. If the Red or Yellow are compromised, the wastegate won't open and the car will overboost, (actually makes it go like a stabbed rat). I'm not sure if your model gets an EML for overboost.

Sticking purely to rubber tubes. The one I would check for the EML is the PCV elbow. With a torch, look into the void between the power steering reservoir and the manifold. You'll see a narrow pipe attached by a rubber elbow to the end of the manifold. This is a common failure that will give you mixture related codes.

There are more perishables to check but it depends how far you want to go. What's the newer blue silcone line connected to out of interest?

[El Padrino]

Yog Sothoth, picking up from what richmac was saying about the diameter of the vacuum hoses, this link has useful information on replacement hose sizes - https://www.ipdusa.com/products/1048...0%20IPD-122041

I was talking to another very helpful and knowledgeable forum member (RollingThunder) a while back about the size of replacement vacuum hoses and he followed IPD's lead and used 5mm hoses and not had any issues since they were replaced more than 2.5 years ago. I'll be replacing my vacuum hoses with silicone ones at some point, but the rubber OEM ones are fine at the moment. You can order coloured silicone hoses if you want to indentify the connections from the TCV easier (as per the route diagram I posted) or do what I intend to do and use coloured tape for an easy fix.

Glad you found the root cause to your issue.