Air/fuel mixture for 80' Corolla

Hi,


I have a RWD 4 door, 1980 model Toyota Corolla. It was purchased in
Saudi Arabia and is now in India (since '93)


It's done about 75000 only and was lying idle for a while. I've started
using it again now and was trying to tune the air/fuel mix, since
lately it was going fast or slow in idle on it's own.


I need help with this since I am unable to understand how to get it
right. There are two screws behind the air filter. I fully tightened
the lower one and then moved it about 1 and a hlf turns
counter-clockwise, below that, the car dies out.
The other one, the one on top/easily accessible one used to make more
differnce to the idling earlier, but now it doesnt make much diff. I've
kept it half way for now, not sure where it should be.


But after I did this, my car is soooo much smoother, earlier it was
sluggish. This is definately the result of my twiddling with the
screws. My priority is to get good mileage, and I think this is not
helping.


I know one screw is for the air/fuel and the other for idling, but dont
know which is which. I need help figuring out how to tune this up for
good mileage on my own. It's not easy to get a good mechanic for these
oldies where I live.


thanks,
Sam