FYI, your bike has two fuel tanks, connecting in series. Anything you put in the fuel tank will take about 100 miles of riding to make it into the carbs. if you want to add a fuel system cleaner, you have to add it directly to the carbs or it won't do anything.
I high idle of 3,000 RPM is easy to get on an engine that's not doing any work. A fuel-starved engine will still wind up to 3,000 RPM if it's just sitting there spinning.
Your carbs sound like they are either plugged up, or the vacuum slides are stuck. If the bike's carbs are in poor enough condition that you can't ride it, I would forego the addition of a fuel system cleaner, and remove the carbs and clean them.
Currently Running Stable:
2010 Honda NT700V
1986 Shadow 700
1986 Honda Trail 110 (Postie Bike)
1987 Honda Rebel 450
1973 Honda Mini Trail 50