Hi all, have just recently bought my first Harley, and have limited knowledge so bear with me on this.... It starts missing after about 20 miles of riding. At anything over 3000rpm it is mostly fine, but when 3k or under it misses terribly. I took it to my local fix it shop, they dyno'd it, and told me I needed a power commander because the Vance & Hines pipes it now has havnt been fitted properly. Today we took off those pipes and fitted the original ones. After 20 miles it started missing again. I have ordered new plugs so will try that as a first option, but if anyone has any ideas why this may be happening I'd love some imput. Thanks, Glenda.