84" Not getting enough fuel during HIGH revs?

[calibretto]

Thanks for your time. My problem is when I go into drive the car into high revs it's losing power at/around 5000rpm. It's choking like it's not getting enough fuel to the engine and loses power. This is only when I floor the gas though. This is really getting old because I can't pass anyone on the high way and I feel like the problem is getting worse. Also, this problem only occurs in 3rd,4th and 5th gear. I have an 84', 5 speed, 12A 1.1L engine. engine has around 130,000 miles on it. The problem doesn't occur in 1st or 2nd gear. I got one guy to look at it and he said I need a new carburetor and that it's running too lean. With thats said Do you have a different answer for what it might be? and if it is the carburetor then how can I fix it. Still has all stock engine(no mods).
Also just changed the sparkplugs today and still having the same problem so it's not the plugs.

[drjoneschiro]

have you checked the catalytic convertor? if its plugged up you wont get any power in high rpms.