I just recently bought some new fuel at the hobby shop the other day. I thought it was only 5 or 10% nitro, but when I flew my plane I realized it had way more power than I was used to. I've never been able to take my Tiger 60 vertical before! But I also can't seem to get my engines to run consistently. Often times they will throttle up just fine for take off but then either right when I throttle up other times or in the middle of flying, the power would sag, or even die all together in one case. I've limited out radio interference because the throttle is the only channel acting weird, and the radio has been in great working order and I haven't dropped it or anything yet. The new fuel is Wildcat brad 15% nitro with 18% oils. It's within the recommended fuels for my Magnum .61 XL. Do I just need to play with the needle valve some more, or do I need to get some different fuel. Oh, and I believe the previous fuel was Byron 5%. Thanks for any help.

Silent J