My car starts uo well, idles between 800-1000 RPM and drives pretty well untill it hits 3000RPM. When i try to accelerate there is a lot of hesitation and it just wont push towards 70MPH in the 3rd or the 4th gear.

The wires and rotor etc are fairly new, less than 6 months.

Could this be a fuel delivery problem or maybe the carbs need balancing?

1973 240Z

Could be , check and or change the fuel filter and see. Also check the screens in the banjo fitting on the carb . Most people toss them but if there still in there they could be plugged. Are you still running the flat tops ? If you are then all bets are off. How about ignition . Are you still using the 240 ignition ? If you are using ATF in the carbs change to 20w or 30w if you don't have the 20 . Next I would check the float levels in the carbs . Is this problem something that just came on ? or is it been just getting worse ? Gary