Land Rover Repair: 2005 Range Rover, head gasket problem, head gaskets

Question
I have a 2005 Range Rover it's misfires in cylinder 6,7&8. I recently had
the head gaskets redone.  It worked fine with no problem for 2 weeks now
the mechanics don't know because they do the pressure test okay.

Answer
Misfiring is three cylinders does not really suggest a head gasket problem as the first choice.  I'd be looking at the ignition or fuel injection. If you look with a factory level scan tool you should be able to see the conditions in the engine and make a judgement as to what's going on.  These cars really need properly trained and equipped service technicians . . .