BC (before cancer), in July, I bought a new to me 2008 990 Adv. Rode it a little before treatments started and during the time that I didn't have the strength to ride so I fiddle farted around with the bike in the garage. The bike did have a little hesitation on acceleration so I wanted to change the fuel filter. I did an oil and fuel filter change and I'm impressed how well KTM parts fit, not like some other bikes I had. So, after removing the left side tank I noticed a space in the upper fairing where something used to be. This isn't a problem since it doesn't seem to affect anything. Then, toward the front cylinder I saw a black hose that at first appeared to be a vent or overflow hose. It looked like someone had crimped it and just stuck it up underneath the tank. So when I put the bike together I put the mysterious black hose and routed it down like an overflow should be. The bike lost the hesitation so I thought I had solved the problem with the new fuel filter. The first time I filled the bike I had gas gush out of the hose and then drip in the garage. Obviously this isn't an overflow hose. So I crimped the mysterious hose and it took care of the fuel leak but the bike started to hesitate under acceleration again. So I have two questions; 1. what is this hose, where does it go or what should I do with it? 2. what causes the bike to hesitate under acceleration? Thanks in advance for any help.