Check your fuel supply first. It sounds a lot like you may have loose crud floating around in your gas tank. Pull the sending unit out and look inside woth a flashlight. If you have flakes floating around, you'll need to at least clean it out, if not going to the trouble of resealing it.

You should also check your fuel filter. If you don't have a transparent one, swap it out. Look at the rubber hoses under the hood and make sure none of them are kinked or collapsed.

You can get a very inexpensive fuel pressure test gauge (it also serves as a vacuum gauge) to see exactly how much fuel pressure you have going into the carb(s).

You may need to go on and tear the carburetors apart, but try everything else first.