I have a 57 S110. it has a 220 engine in it, with a 1904 holley carb on it. At about 1500 rpm it starts chugging and cutting out like it's not getting fuel. On the front of the fuel bowl there is a adjustable metering rod. I've adjusted it at wide open throttle and half throttle. It only affected it at half throttle. If i run it in almost all the way it will drop rpm then backing it out till i get the most out of it i can. No effect on wot. Is there anything else that adjusts the fuel delivery on the top end? thanks.