Fiat Stilo Engine Warning: seemingly unresolveable

I have a 2003 Stilo JTD. A few weeks ago the engine warning light came on. After several visits to garages, a Fiat Franchise found a pair of ladies frillies in the air intake, plus a couple of plastic caps (seemingly the result of some work done by someone before I had the car).

The engine was sooted up, the diagnostic from the ecu suggested some parts needed replacing which have been. However, the problem is still unresolved and the garage suggests having the engine stripped down at five hours labour charge, but says it could end up costing in the region of £2000 (which is probably more than the car is worth).

The car still seems as economical, hopefully with freer air flow (the frillies having been removed!) there will not be the same sooting up.

But what can be done to fix the engine fault economically? Will it damage the car to keep driving it like this, and if so, how long is it likely to last before seizing up? And would the emissions/catalyst be likely to have been damaged by the sooting up (there is quite a lot of soot at the end of the exhaust pipe).

I would start by getting an OBD reader and seeing for myself. To claim a rebuild of the engine after already having diagnosed the supposed error and replaced parts I would be looking to resolve myself. Worked for me in the past many times. My cars new and theres piles of soot on both exhausts.

Is the induction back to how it came out of the factory (ask the garage if you don't know) and in good order.

After that, as Bozzy suggests, the next step is to tell us what the fault code is and then we may be able to help