Check to see if the accel. pump squirts a solid stream without any "dead spots". Sounds like you're not getting a solid squirt when you start to open the throttle.
at cruise speeds if i give it about 1/4 throttle it just stumbles and sputters and pops long as i hold it there. like if i wanted to pass a car on the highway. soon as i stab the gas it cleans right up and takes off. it just started too. i will do the vacuum check on power valve. thats what i think it is or its **** in the carb.