Generally speaking, engine surge at idle usually means it is running lean. Quick way to confirm it is running out of fuel would be to keep a can of starting fluid handy (or WD40, which works just as well). When it starts to die, squirt some down the carb. If it keeps running on starting fluid, then you are running out of fuel - for whatever reason. Your fuel pump may be dieing. If it is, I would scrap the mechanical pump and install an electric pump. The reason is that since most RVs sit for extended lengths of time, its nice to be able to kick the pump on and let it prime, when it has been sitting for a few months. Also, depending on where you mount the pump, it will prevent vapor lock. One other thing, since the mechanical pump has a return line, replace the mechanical pump with an inline fuel filter that has a return line as part of the filter. This will help regulate the fuel pressure, as those electric pumps tend to run a tiny bit high.
