1994 Isuzu Truck

Why wont my 1994 Isuzu truck rev up while driving. It sounds fine idleing, but when i go its like its not getting enough gas. but idk. Please help me.

More info is needed, for instance. Auto or Manual? What engine, how many miles? When was the last tune up done? How old are the air and fuel filters? What does “but idk” mean? Does the truck move at all or does it stall or hesitate?

Which engine? This came with a TBI V6 or a carbureted 4-cylinder (believe it or not in '94). They’re very different beasts.