I want to list these thoughts while I am thinking of them:

1. check the pressure fitting on the crank case for a restriction. I would think the hole should be atleast 1/16th in. in dia.

2. Under the regulator diaphragm there is a soft plug that covers a screen for filtering at the needle valves. Remove that plug and check the screen. I have a rebuild kit with a new plug and screen. I will get that to you. the plug is easy to install. I'll help you.

3.As a final act of desperation, try cutting off a coil or two of the spring on the regulator lever (the forky thing). Maybe there is not enough suction at full throttle to pull in the regulator diaphragm.

Jerry