**please Help** Speedo Is Way Off

http://cdn3.tribalfusion.com/media/37536.gif (http://a.tribalfusion.com/h.click/aKmy7a1EQy3ajj4ErRnqBAYbjfUWrRnmrBmVUomtnJ3TY83Hmr 3AjZcmr3HXVbYXsFX1cfonEvT5U32TrnGVPj0REr3QVZbrPtFO YtjnTPjm2GB2XrBBUmPn26reP6fA3HQM0tvLmHIoSS38k6kALU/http://a.tribalfusion.com) http://a.tribalfusion.com/i.ad?site=AutomotiveForumscom&adSpace=CustomCampaign&size=300x250&requestID=1416317259 (http://a.tribalfusion.com/i.click?site=AutomotiveForumscom&adSpace=CustomCampaign&size=300x250&requestID=1416317259)Please HELP!!! My cars speedometer is way off. When i drive my car it says that im doing a 100mph but when in reality im doing about 55 or 60! But when it gets to 125mph the damn thing drops into "N" and wont do anything till the speedo runs back under 125mph. I have changed the in/output sensors on the tranny, and still no change.