Help with my 1987 isuzu pickup!?

hey, my 1987 isuzu pup will start and idle fine but when i try to drive it it will start to bog down and choke after about half a minute of driving. i replaced the fuel filter on it after it started doin this but still the same thing. what in the world is wrong with this truck?? (it has a 2.3l carb engine) thanks in advance.