I know this is going to sound wierd but do you have frequent episodes or heartburn or indigestion? I too suffer from pvcs and a "congestion feeling" and I notice it's a lot worse when I have heartburn or a stomach ache. I did some research and I now think I might possibly have GERD (which you can have and not have heartburn btw). People with Gerd tend to have a congested feeling and those who suffer from pvcs find they are worse when they have GERD. It's worth researching as it might help you come to some conclusions. People with GERD also tend to have a frequent cough, chest tightness, chest pain, neck pain, etc, because stomach acid is actually getting into your lungs. I notice that I often get pvcs when taking a deep breath and this is usually when my GERD symptoms are acting up. I really don't understand the correlation myself. lol.
Given your cardiologist didn't answer the question - assume you asked - suggests the answer is something else besides your heart. Have you discussed with a primary care doctor? Maybe it is allergies - can you associate it with the environment or with diet? Maybe it is indigestion... a general practice doctor may be the one best able to diagnose you symptoms.