what was your cel?

check for your vac leak between the tb and the head. issues usually are:
1. tb gasket
2. im gasket
3. injector rings

if you had a bad enough exhaust leak before the primary o2 then it could've been giving a false lean reading causing your car to over correct and run too rich. if you've fixed that issue then it should correct the problem. if it's still doing it, but not as much you may have fixed half your problem.

the cel will help lead you down the right path. don't just reset the ecu without finding out what it is first.