EGR Change

[wheeler]

I can only imagine that the DPF being blocked would gunge up the EGR

The EGR valve makes an absolutely fine job of that by itself, it also makes a great job of gunging & blocking up your complete inlet track, even when its working correctly.

Can you access the vac pipe to the EGR valve (either at the valve itself or at the electro valve)? if so warm the engine up & check the air flow reading at idle, should be around 250-300 mg/cp. whilst watching the live data reading of the air flow disconnect the vacuum supply to the EGR valve, within a few seconds you should see the reading jump up to over 500 mg/cp

The MAF is located right behind the air filter in the air intake, really easy to access & replace. Not often you hear those words when working on a C8
The component with the grey plug below

[Rp0thejester]

your not joking, everything is hard work on this car. I'll look into doing that, hoping for good weather this weekend so I can crack on

[PaulC5]

MAF sensors are usually on the engine side of the air filter.

[Rp0thejester]

Thanks for your help wheeler, it turns out it was the MAF at fault, I don't know why I didn't think of that earlier.... actually I do, cos I can't see or even touch the EGR on the C8 so was going in blind relying on modern technology to give me answers. Whose stupid idea was it to put computers in car engines!!! But once again, thx wheeler