I have 65 TTSN hours on this plane, engine , prop, RV 4, IO 360 AV engine. Inherited with the project . As I advance the throttle to almost full forward, just at lift off the engine or prop surges. It droops off for a second, comes right back and we go fly. It does not do it in the air. Have not slammed the throttle forward in the air or on the ground. Things are happening fast at this point so I can't tell you what the tach is doing. The guys who have been working with me are convinced it's the prop. One of the guys is a experienced RVer. He has a few TO/Landings in it as well and confirms it's the prop. We have replaced the governor, gone through the fuel system. If it is the prop I am looking for suggestions on 3 bladed prop. Any other ideas out there? Thanks in advance, I have done a lot of reading, have not contributed. My dues is paid. Ward Combs. 402 871 0039.