One of my buddies has a '96 Discovery w/121K miles and he is having some engine problems. Engine was running fine, then the check engine light came on and it started running a little rougher than normal, especially under acceleration. When he took it to the dealer they told him the check engine codes where for multiple misfires which they claim were caused by "sticky valves". Their recommended fix is two new cylinder heads which are supposed to be of a newer design which helps prevent future valve sticking. Does this sound right, or is it a load of BS?

Yes.

Try plugs and wires first and run some BGK44 or similar, but if a valve is bent you have to pull the heads.

You do not need new heads though. They can either clean the valves and ream the guides or do that and put in the new style valves.

Or just run it as it and drive the piss out of it. That usually keeps the valves clean.

Drive the piss out of the thing with some 44 in it

When you get tired of trying voodoo cures, call me, I can beat the dealer pricing by a long shot. I'm not THAT far from you.

Peace,
PT