UPDATE I replaced the carb gasket and diagram, and the surging was reduced by about 50 %. They didn't look bad other than being dried out and stiff. More than likely the originals from 2003 when this thing was manufactured. I also replaced the thick, black oil that also looked to be original, but no way to really tell. When running, I noticed some gasoline leakage so I just went ahead and replaced the plastic carb completely, finding a new Briggs and Stratton one on line for $24.00. I also received the two new springs and replaced them. Installed a new B&S air filter because looking at this one, it was oily and there was a little bit of oil sitting in the bottom of the air filter housing. No idea where this oil came from, unless the neighbor who owns this thought the filter had to be misted with oil. The engine runs very well now! No surging, idles nicely, and has some rpm adjustment using the throttle plate. Thanks for everyones help and suggestions. I was able to learn a bit about these engines and also help a neighbor.