Rover 400 / 45s and a query

[Scotty2]

Here is our current Rover line up. My 800 has packed in with an immobiliser / ECU issue that I have not been able to sort, so bought a 45, and with little traffic here or MG-Rover Forums I'll ask here as well...
The Rover 400 (420 - T series) I'm still stumped by the rough running of the 400 until it warms up. Seems to run on three until warm despite it starting perfectly on four then going a bit rough until warmed up. I tried changing plugs, leads, CTS, Temp sender, thermostat (last three changed as the temp gauge gets near the red before the fans kick in and recovers).

I'm still banned (long story...) from the brown site so have not been able to get any advice from the masses of older car lovers...

Anyone have a clue why the 400 runs rough until warm?

[leyton057]

I can't be of any help in regard to the 400s running issues, but can I just say, that is a brilliant line up !

And no facelift 45s in site, even better !