Quad is 2008 Sportsman 500 EFI....What happens with the quad is when I first start it up it idles and runs fine after quad warms up I notice a engine misfire at a specific RPM range of 4600 - 5100 below and above this range the quad runs fine. I'm wondering if the TPS has a issue where when it warms there is some kind of defect that is expanding and sending an errant signal to the computer messing up the timing and fuel delivery. When TPS contact is above or below this problematic area on the TPS quad runs fine. I've replaced the plug and plug wire. Anyone have any thoughts on why quad is acting up at this specific RPM range. Thanks for any insight on this.