V7 111 stone 2019. Bike has had very little use over the past three years and i am not suprised that this problem has occurred. Engine starts readily enough no problem. Idles ok. Into gear and the moment the engine is under load it cuts to one cylinder, cant even get into second gear, put it back into neutral and the engine idles on both cylinders. Have emptied the tank, replaced the all metal fuel filter in the tank with a brand new one, replaced the air filter and the spark plugs and put in half a gallon of fresh petrol. No difference whatsover. Seems to me that there is a partial blockage in one of the injectors. I called an engine tuning firm and asked if the injectors could be cleaned ultrasonically, they agreed to do this. On arrival and having looked at them they declined. They thought the process would damage them. I don’t know anything about ultrasonic cleaning, someone just mentioned it to me. Rather annoying as i had to make a special journey. I live in a remote location. So, how do i go about this? Rig up one of those home made contraptions featured on youtube with a valve stem and an aerosol tin of carb cleaner? Forget about a guzzi dealership, there is nothing in these parts. I do not want to buy new injectors that would have to be a very last resort. Apologies if this subject has been covered in the past. I couldn’t find such a thread.
If it runs it’s unlikely to be the injectors,
Check the air filter, then the fuel delivery, fuel filter or pump 
If I may disagree, Phil; based on experience with three BMW K100s it could easily be the injectors. One of those K100s ticked over beautifully but when throttled-on under load it dropped one cylinder and ran badly on another, so it’s possible that
one cylinder on the Guzzi could be delivering just enough fuel to allow for tickover, but at higher demands the stoichiometric balance is thrown out and the bike stalls.
The OP has already replaced the air and fuel filters, so they’re out of the loop. So are the spark plugs and the fuel. That leaves the injectors and, as you say, the fuel pump.
I have to be vague here because I’m not familiar with the V7. I would think that the fuel pump can be crudely tested by detaching the fuel pipe from the injector rail, directing it into a container and turning the bike on to start the priming cycle. If it’s delivering okay then there should be a fairly hefty gush of fuel.
I also have another reason for leaving the injectors in the suspect loop - E10. If the bike hasn’t been used much then the injectors could be quite literally rusted up. I’ve bench-tested injectors where I could hear the coil whining but the gate was simply not opening far enough to shoot enough fuel though.
You could try a bottle of injector cleaner in the tank