I have a 2007 Ultra Classic w/18,000 miles on it. Last month it started taking 4 to 5 seconds of spin before it would start. I've heard several things it could be, (i.e. fuel filter, fuel pump, fuel injector, etc.) but not sure how to check each specifically. Any tips on how to narrow this down? Here is whats on the bike; PCIII, K & N air filter, V & H true dual head pipes, supertrapp se exhaust. I just recently checked the code readout and had to replace the rear o2 sensor.