Duffs,
Mine is a standard 3.5 flapper type injection plus 8 but I am happy enough with the performance and I haven't heard complaints of the symptoms you describe amongst other owners with hotwire.
When I ran a V8 Range Rover I did have ecu problems which required a refurb/recon. My recollection was that I sent the ecu away and it was checked to confirm that it was faulty before the work was done. The expert seems to be Mark Adams although I have never used him myself.
If you lived closer to the Midlands then I would recommend Kevin Vernon (Tudor Motors) without hesitation. Many people treat the electronics as a black art but Kevin seems to understand it!
If it were me I would get the car running properly as standard before spending too much on upgrades.
Maybe the dealer should be the first call!
Enjoy your car...
Malcolm
