1990 Toyota Tercel - Redline Weber carburetor better than original 1bbl venturi?

[Karl]

Hello. My mother has a 1990 Tercel with 80,000 miles and a venturi type carburetor that is now starting to act up on her. The idle goes high then down and the car seems like it is lacking power as well as running a bit rough. I replaced the wires, plugs, cap, and rotor and it was still acting up. Told her to use hi grade gas and put carburetor cleaner in the tank, but unfortunately the car ran the same. She took it to her mechanic who has done work for years for on her cars, but he said that she should take it directly to a Toyota dealer to have it serviced. He said that those types of carburetors are notorious for problems and she may need another carburetor. Taking it to a dealer could run some money so I figured that maybe a carburetor swap would be a better idea. I saw the Redline Weber carburetor online and it looks like a nice unit. Her car is an automatic with air conditioning which seems to make a difference which carburetor is used and this is something I have no idea about. My question is has anyone swapped their original venturi 1 bbl carburetor out for a Redline 2bbl Weber? If so is the conversion hard? How does it perform? What is the difference between one made for a manual transmission and an automatic? She only wants the car to run a bit smoother and of course with a normal idle.