I had a problem with the regulator on my home furnace freezing up the first year the furnace was installed. (Boy it really sucks to run outside at 20 below in your underwear at midnight to dump hot water on the stupid regulator) They were able to fix the problem by adding some sort of a certain antifreeze / water absorber to the propane fuel in the tank. (I'm thinking it was methanol but, I'm not sure) After that it hasn't froze up in years.
You may have moisture in your propane fuel system. Unless you get it out you will continue to struggle. Changing the regulator might do it, and they are cheap. But, if you are still using the same propane tank that has the water in it you might just end up having the same problem again. Do you have the smaller tanks? If you do go get replacement ones from one of those exchange places like Blue Rhino. You may still have to replace the regulator to get the moisture out of it though. Or, maybe your tech guy can disassemble it and clean it.