Toyota Repair: 1972 F-40 Landcruiser, intake manifold gasket, vacuum system

Question
Hi,

thanks for the service you provide!  my cruiser has only 102,000 original
miles and normally runs great.  It started to miss and backfire recently and
the
engine will quit if not run without constant throttle or manual choke applied?  
this happened all of a sudden and no prior problems?  I checked the ignition
timing, points, and plugs and all was well.  The vacuum system is working as
well.  This leaves me to the carb or fuel filter?

Any advise.....???

Thanks Again!  

Answer
Check for an intake system air leak, especially at the carburetor base and the intake manifold gasket, spray some carburetor cleaner on the suspected areas and see if there is an increase in the engine speed, if so then that's were the leak is, if that's not the case a tune up which would include replacement of spark plugs/wires, distributor cap and rotor may help.