I have a 6-top Kitchenaid burner that I have converted from natural gas to run on LP or liquid propane gas. I am trying to use it with a BBQ-grill propane tank, but when I connect it to the stove, it does not put out enough gas to run multiple burners, it can barely run one. I am guessing this is caused by the regulator on the hose. How do I adjust the pressure? Should I leave this up to a professional? What type of professional would I contact to handle this? Thank you

If there isn't a company like your power company or a propane supplier who will help, I would call a plumber. They do gas lines as well as water lines.
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Did the conversion parts come as a kit with instructions? If so, did it give the pressure and volume you will need for the stove? It seems to me like a typical barbecue should use as much or more propane than a single burner. There is also volume. The small hose on the tank may not supply the volume needed for very many burners at once. You are either going to have to dig up the specs or somebody that knows how it should work.

We have a number of good people in H&C. Maybe one of them has enough propane experience to help.