audi 80 coupe wont start?

[the1pongo]

my father in law has an 80 coupe, the other day it died and now wont start. Before it died it would miss when warm. Now when you try to start it it struggles to fire, there is fuel going through to the combustion chamber and there is a spark at all 4 plugs.when it fires it sounds hollow and laboured. it is an N reg 2litre. Can anybody help please.

[scotty33]

There could be a short circuit on the wires for the oxygen/lambda sensor. Has the sensor/exhaust been worked on recently?
If it is the problem, it will run better with it disconnected. If so fit a new one, running it for long disconnected (or misfiring!) damages the catalyst.. It may also run ok (ie rev up normally) at wide open throttle.