Previously I was having misfires at low RPMs so I change all the spark plugs on my 2005 Yamaha R6. After I changed them the misfires went away but now when I get it up to 80 to 90mph it stops accelerating and sometime would shut off the engine. Could this be due to a loose spark plug or could I be having bigger issues. I will go through and tighten them tomorrow but just wanted to get a second opinion. Thank you for your help.