Daewoo Nubira 1999 error code P0172 on 2004 Suzuki Forenza

I have a 1999 Daewoo Nubira Wagon. It has the same engine as a forenza. I get error code P0172. The car runs fine on flat land and can go 80 mph with no problem. But when i go up the in the mountians the car is very slow and smells like gas. This car use to take the road to Big Bear Ca, with no problem. Now it stinks of fuel when going up the hills. It does not smell or have a problem on flat land. What can I do to fix this?

Asked by for the 2004 Suzuki Forenza
P0172 is code signifying the engine is running tom rich. This cold be due to a bad coolant temperature switch, restricted air filter, bad fuel injector ect....
A profession auto scan tool reads fuel trim, Oxygen sensor values, actual coolant temperature values as seen by the computer in your car, just by reading the information on the scan tool.