Well the thing it would probably be is Inflation I don't know what those factors are in Vanila, but did you change either of them?
If the Offset was positive before, a bigger positive number would mean LESS inflation and a negative number would mean more.
If the Offset was negative before, a bigger negative number would mean LESS inflation and a positive number would mean more
The Inflation % is directly tinked to inflation (bigger=more inflation)
Otherwise you could have just played poorly and over expanded. (you do know about city maintenance right?)