I recently rebuilt my carbeurator on my 1989 Toyota Corolla. I've re-installed it, but think it needs some adjusting. When I start it up it starts fine, but when I turn off the key it sputters and squeaks before turning off. It usually takes about 5 seconds to stop. There are several adjustment screws, but I don't know where to start. The engine is a 4-AF. The carbeurator is an aisan. I've adjusted the idle screw (the one that you can adjust with your fingers on the back of the carb), and I think it's ok. When I first re-inserted the carb, the car overheated really quick. I did correctly install the gasket on top of the intake manifold, and it was the right gasket. I changed the thermostat and the radiator cap, and the problem seems to be fixed. I'm not sure if that might have something to do with it though. I guess the major question is, how do I adjust the carb so that the car stops when turned off, and doesn't sputter or squeak?

Optional Information:
1989 Toyota Corolla 4-AF

Already Tried:
adjusted the idle screw