[steplift20]

I am having an issue at low and mid range with surging. Top end she runs like a champ. Coming off of plane and low idle, she surges. I inspected spark plugs, coloration all the same no signs of lean mixture poured gas from water separator in glass bowl, no visual debri, checked oil level and coloration , looked good. traced a blue and yellow wire located under the throttle linkage under cowling to the fuse cover on engine. Upon removing fuse cover, a grey connector with a black jumper wire fell out. I know it fits on the diagnostic connector location ( this was the only one without anything installed ) and am not sure if I should connect it or should it be left out?
Could this be my issue?