Landrover Discovery V8i L Reg

Quite possibly.

Check the temperature and Lambda sender connections are clean and not oxidised or damaged. The wiring loom is poor quality on EFi Landrovers ( Jaguars of an age as well ) and gives rise to a great many misfire/timing issues. If you can, when the misfire is apparent manipulate the sensor plugs to determine which may be giving the problems replacement plugs are available from Lucas Service Centres, very cheaply last time I bought a couple. Do it sooner rather than later I found my RRC bloody heavy to push off a junction when I had a similar problem.

Derek

To further expand on my somewhat terse post earlier (work started hassling me on a Saturday) an exhaust leak upstream of the lambda sensor can introduce air into the exhaust thus upsetting the lambda sensor reading and causing a misfire. Fix the exhaust leak *before* you do any other troubleshooting.