What if a police officer pulls you over and they cant find a reason to issue a ticket?

If the officer pulled you over then he had a reason otherwise that is illegal. He can issue the ticket based on that reason. That is called probable cause. If an officer pulls you over and can not articulate probable cause then he must immediately release you because it would then be an illegal detention.

Another View: In many (most?/all?) states officers are allowed to conduct random 'spot checks' of motorists to determine if they are operating in conformance with the state's laws regarding proper licensing, registration and insurance compliance.