Just rebuilt 06 efi 500 Sportsman idle is good, for trying it out took thermostat out as damage before was caused fron running hot, and I forgot to pick one up. First took off ran okay just taking it easy 25 to 30 mph as I rode it it started surging or jerking worse and worse, keeps it at a slow speed and it would run smooth try to hit the throttle wide open and it would fall on it`s face no check engine symbol have not checked for codes. What do any of you think.

 

Found problem it was the pig tails coming off the main wiring harness they go to the idle air motor, throttle podition sensor, and the map , also have a speed sensor bad