copied this from carb tuning guide, kinda sounds like ur problem
Does it hesitate and then rev up?
As it comes back down to idle, does it seem to hang at a higher idle for a minute and then settle down to normal idle?
If it does this you're Too Lean on the Air Screw adjusment. You need to richen it up by turning the Air Screw IN 1/2 turn and then repeat the test.
Adjust as necessary, repeating the test until you have a nice response.
Or
Does it sound like it bogs a bit?
As it comes back down to idle, does it seem to drop to a low idle (or even die) and then come back to normal?
If it does this, it's Too Rich. Turn the Air Screw out 1/2 turn.
Adjust as necessary, repeating the test until you have a nice response.
Remember: Adjust the Air Screw in 1/2 turn increments at first then fine tune with 1/4 turn and then 1/8 turn increments.
Repeat the proper adjustment until it responds without hesitation and drops back to idle without hanging or falling and then coming back up. Expect to do the bottom end adjustment at least three or four times before you get it right.