I would try using premium gas and see it helps the engine run smoother. My 2015 5.0 engine ran like crap with the regular gas that the dealership put in it for my test drive(salesman stopped at a Racetrack to fill during the test drive). It idled rough and felt a bit sluggish with the 87 octane. However, I took a gamble by buying the car hoping the that the engine would feel stronger with premium fuel and was not disappointed. The engine runs buttery smooth at idle with Shell 93 octane.
As the pistons build up gunk it often decreases the overall volume, thus increasing the compression every so lightly; to the point where using higher octane fuel makes it run smoother.
Remember, higher octane fuel doesn't mean that it is a better gas, it just means that it takes longer to combust for higher compression engines.
It's not uncommon for higher octane gas to make engines run smoother that has built up gunk.
I normally do not use any extra fuel additive since Shell V-power 93 is supposed to be loaded with extra detergents(7 times the required amount) per the Shell website. However, it can not hurt to use a bottle of Techron in the tank every so often to provide some extra cleaning, so I make try it a couple times a year to help keep my fuel injectors clean.
Shell V-Power NiTRO+ Premium Gasoline
I used to be a hard core Shell fan and at one point and one of my cars only sipped on Shell until I sold it. The claims by shell are simply "claims." No one really knows, because petrol companies are hiding behind the whole proprietary nonsense and not being transparent these days.
I do think that Shell despite their claims remain the King of the Petrol jungle hands down, but over the years and due to the 4% cash back at Costco, I make my own Shell by just adding Techron full system additive every ~3K miles or so lol.
All the raw petrol is the same across the board, with the difference only being the additives each company adds to it. So instead of paying upwards of 50 cents more per gallon, if you buy a bulk of 20oz Techron for ~$9 a bottle (w/ 5% Amazon cash back in my case), you'd be on par with breaking even after only 18 gallons of filling up on Shell, which is pretty much one fill up.
I've always looked at it two ways.
If you use Shell and IF it really is potent with its claims then you're constantly cleaning and maintaining that, which is good.
If you use the Costco + Techron every ~3K method like I am, then maybe it's not cleaning as much consistently, but when it does clean on that full tank w/ 20oz of Techron... is having that concentration to 'shock' clean the build up as effective? Who knows...
If you want to go all out, use Techron every few thousand miles on top of Shell to have Pearl Fuel.
I would add the Techron to a tank that you expect the burn right before the next oil change.
Indeed. That's what I normally do. Depending on the season I'll go through about 3-4 Techron treatments before an oil change. Sometimes my oil change internals overlap with the fuel treatment... I keep it pretty ball park estimate...
About that Italian treatment... usually on the tank before my oil change I'll take it for a good spin to try and burn off all the gunk.