sorry I meant to ask what the filters micron rating was. There should be two filters/strainers on a fuel system...one before the pump and one after. The one before the pump (except in some gerotor type pumps), the micron rating really shouldn't be lower than about 75 or so. The reason being is that much smaller of a micron filtration can restrict flow to the fuel pump/carb and will actually make the pump work harder and not last as long. These type of strainers are generally placed inside the gas tank where the sending unit is.
There should also be a filter between the pump and the carb/fuel injectors with a smaller micron rating around ~30 or so for carburetors and even smaller for fuel injection as the injectors are more prone to clogging. Its easier for the pump to push the fuel than it is to pull it through a filter.
What I'm trying to say is theres a possibility your filter could be too restrictive, causing a lack of fuel volume and/or pressure at a high load, making your carb not get enough fuel and misfiring.