need help please guys,, the tps all ok well within values, the problem is it runs idles ok but has a real bad flat spot at 3500 rpm, you open the throttle quick and it boggs down and stalls but if you do the revs slowly it seems to go throught it, the carbs have been pulled out all jets checked all clean float hights ok , fuels ok just stumped

thats normally a sign of a lean pilot mate or even a small air leak, causing the same issue, do the revs hang on the way down too? you got air screw adjustments on your carbs? try turning them in a bit ......and raise the idel with the idel adjuster screw. also try squirting some wd40 around them, see if the idel drops.

you balenced your carbs too?

Check the carb top diaphams aren't split and that the little o rings at the top are in and are the right size to seal properly.