4.2 Supercharged misfire

A long time landy owner but this query is about my other car which is a Jag but has the same 4.2 supercharged engine and ZF gearbox as a Range Rover which is why I am here. I have a misfire at about 1800rpm, particularly noticeable when cold and engine under load like going up a hill. Doesn't seem to happen when the car is fully warm. I can see the rev counter pulse by about 200rpm when it happens but put the box in "manual" so the revs are higher and its fine. I am not getting any clues from the Jag forums and wondered if this might be a common problem that's known to RR owners? If not sorry if I have wasted your time.

You sure it is a misfire and not a gearbox/torque converter problem....

The earlier L322's with the BMW 4.4 V8 and the ZF 5HP box had TQ issues which caused misfire like stutters and TQ judders....this was due to the TQ friction material wearing out on the Lock Up Clutch Plates....

Misfires will cause the MIL/CEL lamp to flash and if really bad, through a fault code....have you had it on Diagnostics?

That's occurred to me about it being gearbox related as diagnostics revealed nothing. Would torque convertor problem only be evident when cold?

On the Range Rover at first it only happens when warm....but if left it starts to happen at any time!

If the same applies to the ZF box in the Jag - there is a warm up cycle when the box is cold, this is to get the oil up to temp as quick as possible.....my BMW fitted with the ZF 5HP box seems to stutter when cold unless you give it some beans.....as this uses the same warm up logic that my L322 does....basically because they are almost identical cars!!

I had read something about a warm up cycle but if that is what its doing then it cant be doing it right as its far more noticeable than I would have thought it should be.