I have experienced Lopeing At freeway speeds and hills/underload with my '80 manual 20r. Drives fine around town but the hill on the freeway going to work is a killer. I have put a new fuel filter, fuel pump, Weber carb, distributor, plugs wires, Ignition control module. And still nothing has changed. It has to be something simple. I have a dual port vacum advance and only one spot on the Weber, thats what I was thinking, the timing is not advancing as the gas increases so that causes the lopeing, but I really don't know:headbang: I have the hose on the vaccum advance side of the dashpot and capped the other. Also if i pull on the manual choke it helps for a few seconds then makes it worse.