My Adv 990 was the same and the reason I only kept it a year...But that was 2008...Have they still not got it sorted
I don't think anyone has it sorted these days, Euro 5 makes it very difficult to fuel a bike properly, a miracle they run at all! Big twins dislike very low rpm / low throttle more than triples and fours when running piss weak.
Often the rider can make it worse, if they do not understand the purpose of a gearbox and the revs at which the bike works / responds, you are more likely to get away with riding a 4-pot at 30mph in top gear, but a twin cylinder needs a few more revs to smooth out, dunno about the 790, but to do 30 mph on my GS / S10 / KTM 1190 I really needed to be in 3rd gear, (and the GS still surged and popped in protest before I fitted a dongle to add some fuel) the 1290 will run quite well in 4th - but 30 is better.
A remap will almost certainly fix it, but these days you might need to go full Power Commander with O2 Optimisers (Wideband Sensors) and spend a big chunk of money (and put your insurance premium up)
To give an idea of what the manufacturers are up against see theimage below.
It seems to me things were pretty good by Euro-3 and Euro-4 had as good as solved the issue, Euro-5 I think is just because some European Bureaucrats are getting paid a fortune to just keep knocking a bit off every couple of years - and I suspect the extra (environmental) costs of making catalysts and other control systems plus people just revving the tits of their bike as it refuses to run properly below 5,000 rpm actually causes a negative results even before we rip this shit off to fix our bikes.
It is also well known many catalytic converters will never pay back the carbon footprint of manufacturing them during the vehicles lifetime, but this is not really about saving the planet it is purely to hit some targets for city air quality (Ban cars, give free tax to mopeds would solve this) and if that means much more shit in the atmosphere in China where the catalysts are made then so be it.
Rant over!