Engine loses power for few miles

Hi I have a 2016 registered metropolis Freelander, it's started having a issue , I
I'm driving day 65/70 and suddenly the engine power drops right down, it won't lick up, maybe last a few miles then suddenly kicks in. LR dealer day nothing shows on diagnostic . AA breakdown said it needed a new ERG value cost me £600 on AA breakdown report at garage took it for a test run and done it again. Now still in garage trying to find fault. Not LR garage as they charge £180ph labour and previously couldn't find fault. This is dangerous if it happens pulling out of a junction which it had done a few times. Do I sell my LR as getting really fed up as o my had it four years and cost me 24K from my LR garage. Any help please from anyone here as I'm getting desperate Thanks for reading .

Sounds like electrical to me, maybe the MAF sensor, having said that though in the four years you have had the FL2 as the fuel filter been changed?

Whereabouts are you in the UK how old is the battery.

Try it with the fuel tank cap removed.