Oversteer

Hey guys....Here is what I'm looking at. I have an '88 TII Convertible. The engine is stock '88 TII and I installed an S5 Turbo. The engine compression is fine. I've got a Bonez downpipe and cat as well as a new O2 sensor, and an FCD. The plugs were replaced as well as all the vacuum lines. The timing is right on. I took the car to get emissions tested and it failed miserably. When you get on it with the top down, the exhaust smells very strongly of gas. All the emissions equipment is still on the car. I've traced the engine harness back to the ECU to make sure I didn't have any breaks in the harness. Does anyone have any ideas on what would make the car run so rich?? The gas mileage is pretty bad too.

Any help is greatly appreciated.

Oversteer

Anyone know how to test the water thermosensor and thermoswitch?