Please help solve Poor Radio Reception

I have owned my Acura Vigor for 4 years. The Radio has never been right. I have replaced the Radio x2 I have replaced the antenna and the antenna lead x 2. I have taken it to Best buy x 3 (They did the original install) and gave up and took it to a independent shop. I installed a add on Visteon HD radio. Still the radio is no good. The signal is variable. Even when the car is not in motion. There are definite dead spots that I always loose the signal.  I cannot spend any more $$$ on this. Please Help me. What do I need to tell you ask me anything.