The MAP sensor looks like a little black plastic tab on the back of the inlet manifold. It’s in the middle, under the plastic engine cover. It’s held in with one bolt from memory.. then to physically remove it you just pull it out backwards, away from you, since it has an short stub which fits into a hole in the manifold. You’ll see it, since it has wiring going to it.
Clean it out with electrical contact cleaner after a soak with WD40 (since that has kerosene in it) then let it dry out.
The exit pipe that’s full of soot/gum can be cleaned out while you’re there but there’s nothing in there that knows how much flow is passing through the EGR, so the scanner error must be a generic EGR error. If you think about it, there’s no difference between a blocked pipe and a blanked off (with plates) EGR... which doesn’t give errors, so your problem is not insufficient flow through the EGR.
Similarly the MAF down by the airbox and the lambdas have no idea what’s happening up top... they deal with their own parameters and if they can’t adjust for some strange behaviour they’ll give their own errors.
Anyways, clean out the MAP sensor first... and the corrugated pipe... check the EGR is still connected/nothing strange has happened to it
And then take the beast out for a short run but when you accelerate go up to 3500 occasionally where it’s sensible, to get some swirl through the intake and flush out any loose carbon etc.
On my old beast you’ll be pleased to know that I had to buy a new MAP sensor since cleaning it didn’t solve the problem... but see how it goes cleaning it first.
There’s no need to clear the codes... they’ll disappear when an error is no longer detected after a few check cycles... but it’s useful if you changed something and want to know immediately if the error is still there.
Ralf S.