Lern me gas tank cleaning

The easy way

Trying to make my old CB175 run and I think the fuel tank is the issue. It seems to run okay after cleaning the carbs, bolting them up and starting it but the more I run it the worse it gets. First crank on clean carbs it will fire and idle and 20 minutes later it barely will start or hold an idle and stalls once the clutch starts grabbing.
Super frustrating. 

So I'm going to clean out the tank and try some fresh fuel. I've seen a few tank cleaning methods on here but I can't remember what they are. Anyone have some tips for me?

At this time I'm not looking to restore this thing to new. I just need it to run reliably. 

Throw a bunch of nuts and bolts in there along with some water. Shake, rinse, repeat. Vinegar works to get the rust off, but you may need a Por-15 tank sealer, Kreem, or something of the sort.

Also heard of people using pea gravel or BB's with a quart or two of gas and then shaking, let sit, shaking, let sit, repeat repeat over a few days. Could probably use Evapo Rust instead of gas.

The inside of the tank doesn't appear rusty. It's an odd shape to fit around the frame so I can't see every angle but I think it's mostly okay. Are the hard bits still necessary? Just curious

I haven't actually seen any corrosion in the tank or the float bowls but my hunch is that there is still something very small in the fuel.