First of all they will not kill you. How frequently are you getting them? How many per hour or minute do you think? If you have eliminated foods you like and it didn't help then don't worry about them! My story sounds a bit like yours. Mine come and go, I've had them for years. Some days I have pain with them as well, but everything has tested okay!
Unfortunately an EKG is not sufficient to know if your PVCs are benign or not. You also need to rule out underlying causes for the PVCs in the first place. That requires an echo (to check for physical defects, valve issues, ejection fraction, enlarged heart, etc.) and less importantly at your age to check for blockages (so like a stress test or cardiac CT scan).
What you know for now is that you have PVCs and they are annoying you. Most likely they are considered "benign" (in quotes because we all know how annoying they are) however whenever you can, you really ought to rule out any other underlying issues.
Now, all that said, many of us have tried what you describe to stop them. We've stopped caffeine, we've stopped alcohol, we've cut out spicy foods, we've started taking magnesium, calcium, fish oil, potassium, etc. Many of us are on a beta blocker or have tried a BB and given up on them.
So how do you stop them? Good question! It seems to be kinda unique to the individual assuming you can't find an underlying cause from the list of tests above. For me, it seems that extra Taurine and L-Arginine is doing the trick (1.5 months practically PVC free after thousands a day for 9 months). @tronius reports that gasx seems to have done the trick there. It seems to take some experimentation.
With regards to the beta blocker, I take 25mg of Metroprolol ER. You need a prescription for that and it probably won't stop the PVCs. What it did do for me is make the follow-on beat after the PVC less forceful and less annoying. This made falling asleep easier.
Anyways, keep the search up for the cause as you may very well find something that works!