I have a carberated merc 100 that will not run below 4000 rpm unless you keep hitting the choke(tickler).It started after the fuel pump went out. I rebuilt the pump and replaced all fuel lines while I was at it . The pump seems to be mixing the gas and oil properly and has good pressure , I've purged ALL fuel and oil lines, checked for vacume and fuel leaks, the only thing odd about it is the top two carbs don't seem to be drawing (sucking) as hard as the bottom two . The only thing I can thing of is maybe a bad reed valve.any sugestionsor input would be greatly appreciated. Jeff