Since the bike only had 9K on it after 6 years it obviously wasn't ridden much. It may have sat unused several years before the guy decided to sell it. In that case water will build up in the fuel tank and cause rust.
You might try opening the drain plugs and catch the drainings. Look at the drained gas to see how much particulate is in it. While the drain plugs are off spray some gumout into the bowls to fluch out as much as you can. Then reassemble. Also you can try some mix-in-the-gas carb/injector cleaner. Don't forget to replace the fuel filter as it may be clogged.
Also you should drain and flush the fuel tank to get rid of any accumulated rust. Never leave the bike for long periods with the tank partially full.
Now try riding the bike again. If it hasn't improved you may have particles stuck in the internals. In that case you have no choice but to remove and disassemble the carbs for a complete inspection. There's a myriad of things that could be wrong... leaky float, cracked boot, etc. These jobs are not hard to do. Just get a Clymer manual and follow the instructions.
Check and make sure the equalization tubes for the Ram Air are hooked up properly. There's a little tube that runs inside the ram air ducts that equalizes the pressure in the carburator float bowls as you increase your speed, and the pressure inside the air box increases.
Otherwise check the float height in the carburator bowls. If it's too low, you could run out of gasoline at high RPM's.
Ask yourself these questions and then follow the path that the answers give you.
If you are running out of power between 6 & 7K in low gear, then chances are you don't have a fuel problem as the engine uses very little fuel between idle and 7K in first. If the engine appears to be losing power in one of the higher gears, then it could be a fuel problem or a spark problem. Hard to tell the difference unless you're familiar with symptoms of this type. Easiest fix for the latter symptom would be to replace the plugs. If that doesn't solve the issue, then you can pretty much count on the fact that you have a fuel delivery problem.
Any garbage that's found its way into the float bowls will pretty much clog the idle system first, as that's the one that's being used the most, so I'm not big on that theory that some posters suggested that the problem lies with the main jets. I'm going with plugs, but whatever it is, let us know. It's always fun to see if Troubleshooting-By-Mail works.
Thanks for everyone's help. Yes, I realize I shouldn't have ridden it this long etc... It's a problem that's been easy to ride around on the street. I plan on doing a major tune up to it which will include new chain and sprockets, plugs, pipe, jet kit, fork fluid replaced (possibly revalvled), head bearings, and valves. Should be ready for a track day in August. I'll let everyone know how it works out. I'll start by cleaning the carbs out first and the plugs.