My RR is backfiring and acting sluggish at startup. After I drive it
a few miles then it runs fine...though it does seem a little weaker
sometimes. Usually this only happens in the morning, and won't
do it at any other times during the day.

Let me know what you think.

 

air/fuel mixer sensor not quite quick enough. fuel pressure sensor. temp sensor. the timing advance not resetting. You could spend a year on the diy page and still be looking. see if someone with the uplink can point you in the right direction. The back firing thing can be a long term problem if not addressed. fire ain't suppose to go that direction. hope it helps. gotta love a rover. duboff