Have a John Deere LA105. Will not stay running unless the vacuum line from the fuel pump to the oil stick line is unhooked. Have cleaned carburetor thoroughly, changed fuel filter, fuel pump, all fuel lines from tank, new battery, new air filter, oil filter and oil. Also fuel filter will not fill up completely. Any suggestions? At our wits end. Will crank and run, but as soon as you reattached the vacuum line, quits.