i have a 03 f150 lariat and the speedo just went to 100 mph , if i get up to about 55 , it reads 80 mph lol and hints on how to fix it please thanx

 

Gauges on this generation were prone to circuit board failures. This is something only a gauge shop can fix after you pull it out. Honestly I would just get a used one at a wrecking yard ($25 to $50) or buy a set online for about $125.