Hey there Abogart welcome to the site! I too am from Michigan and also own a 3100 v6 which is in my 95 Grand Am. I must correct a few things tho. You have a 3100 SFI V6 in your Corsica and 179k miles is just breaking that motor in
. I am sitting at 311k right now and no signs of it quitting. Your car is about 200lbs less than my car so that will help a small amount. I too have a 4spd auto and they are actually very smooth and economical. I have found they get better mpg if you slowly get up to speed and stay around the 45-50mph mark. On the highway 63 is the sweet spot it seems. I can average 34-37 on straight highway at that speed. Cruise kills mpg for the fact it accelerates up hills and slows you down going down them so I don't use it. Check out my fuel logs and if you need any more pointers tell me
.