Last week on a railroad grade with temps high 30s to 40 degrees my sled initially pulled hard to 7300 rpm. At about 103mph the rpm began to drop slowly 7200, 7100, 6900, and then to 6700 before I let off the gas. Motor was running smooth but when I hit it again the valves didn't open. No code flashed but there was no change in exhaust note nor the increased pull when they open and revs were stuck around 6700-6900, sled barely hit 90. Rode slow for another 5 or 6 miles and hit it again. This time the valves opened normally and acceleration was normal. Got home and cleaned valves but they weren't bad, before removing them I pulled the cables and they worked normally. Has anyone else experienced this without a code flashing? I'm going out to the garage to check the wiring for any abrasions. I saw a couple posts where there were some shorting issues but don't know if any codes flashed. Sled's an 07 F1000 with y-pipe and bullseyes.