I would try priming the fuel system, maybe you just did not get all the air out when you previously changed the filter. However, if it starts after priming and then later won't start again or stay running, then you may have a fuel system leak. If that is the case, I would pressurize the fuel tank with ~ 5 PSIG of air. Then look along the fuel lines, by the filter housing, etc. for the leak. If you do not find a leak, then maybe you just need a new filter. If replacing the filter and priming gets it started, then maybe you did get a load of bad fuel. You may have to drain the fuel tank, if a new filter plugs back up.