Land Rover Repair: 96 Disco Misfire, carbon buildup, engine temp

Question
I have a 96 4.0 Disco SE. The coil packs have been replaced, new plugs and new wires. The LR has 87,000 miles on it. After about an hour on the interstate the enginge loses power for a few seconds and then runs fine for a few seconds. It does this for a few miles and then it will be fine for another long period of time. Then it might do it again. It seems to happen more frequently when I accelerate. The check engine light is on and the mechanic told me it was a misfire code. This happens at about 70-75 mph or from take off. Any suggestion would be great.
Thanks
Patrick

Answer
Hi Patrick,

this sounds like the exhaust valves are sticking...a common problem with 4.0 engines.  Valve job is the only cure.

It is reported that carbon buildup can stick to the exhaust valves causing them to stick as they are seated.  The result is misfires, loss of power, stalling.  You may see this more on hot humid days, while climbing hills and usually at optimum engine temp.

Best of luck,

JohnMc