I have an Avanti gas range that is converted to run on LP. I flipped a cheesy plastic part on the regulator attached to the range and switched out all of the orifices. The thing fires up but is incredibly weak. It takes forever for the oven to get to temp and can't even get to 425 degrees. Called the manufacturer, they said it was the thermostatic valve and sent some one to replace it. Here I am, new thermostatic valve and same problem. There is a two stage regulator running from a 20lb tank that feeds into the regulator on the back of the stove. I have a feeling this is killing my gas pressure. Any help is much appreciated!!