misfire RR Vogue 04

Hi guys got a bit of a problem on my RR Vogue 2004 V8 petrol, had a misfire and broke down the other day as it just cut out and wouldn't run right at all..I got it home change the coils and plugs so it's better but still not running 100%. On checking it with two different diagnostic machines snap-on and autel both still register no.5 cylinder misfire even though I've swapped coils ...on doing an injector test all proved to be correct and working right however on disconnecting the coil feed cable it made no difference so I'm thinking a some sort of control module issue or valve ? Help

Check wiring continuity to the coil oand/or injector....might not be getting a signal.

I'm sending it to the auto gas place where the conversation was done 8 years ago, the local 4x4 place reckons they'll have a better idea where they tapped in to it for the lpg system, he too suggests it may be a wiring issue..