Small Engines (Lawn Mowers, etc.): Briggs & Stratton stalling, briggs stratton, old briggs

Question
A house I recently bought came with an old Briggs & Stratton lawn mower with some problems I've been trying to fix. It's a Sprint 3.75 hp bagging model, built in 1994. It was struggling to start and constantly stalling (every other row when mowing). I did the usual things, changing the corroded spark plug and a crusty filter, but it continues to stall, although not as often. There's plenty of oil in it and the gas is new and I see no sign of water in the tank. That's about as far as my knowledge of mowers goes. I can also say, if it helps, that the thing will run only with the throttle all the way open. Any less and it'll stall pretty much instantly. It generally starts on the second or third pull and now it stalls only every five minutes or so. Each time I have to re-prime it to get it running again.

I really appreciate your help.

Answer
Not sure which engine model you have but my guess is the carburetor is the most likely problem.

Does you carburetor look like this one in the video?

http://www.youtube.com/watch?v=HDQ0elcCOlY&feature=related

http://www.small-engines.com/choke.html

http://outdoorpowerinfo.com/repairs/briggs_pulsa-prime_carb.asp

I would start by cleaning the carb with compressed air from an air compressor and replacing the diaphragm.

Let me know if the links help.

Eric