1984 Other Volkswagen Models

Engine Performance problem
1984 Other Volkswagen Models Engine Size unknown Two Wheel Drive Manual 160000 miles

The vehicle is actually a 1984 VW Quantum with an inline, overhead-cam 5 cylinder engine and is front wheel driven.

I have not driven the vehicle in 2 years, but fired it up the other days without any issues. The reason I have been unable to drive it is because it will not pass emissions because the OXS (check engine) light remains on. I had to let the vehicle sit as changing out the sensor on that car was really difficult and I did not have any time. I changed the oxygen sensor (with great difficulty) recently and the light still will not go out. I have checked the fuze for the oxygen sensor and it is not broken. In fact all of the fuzes are not broken. The vehicle idles fine and there are no smells of excessive fuel from the exhaust or black smoke being emitted by the exhaust. The oxygen sensor appeared to be a direct replacement, i.E. One wire that easily connected to the vehicle's wiring harness and they looked the exact same. When I rev the engine up to 2,300 RPM the idle comes down back to around 750-800 RPM normally, i.E. It does not linger at a higher rpm or drops slowly. The vehicle did contain old gas in the tank of which I will drain and replace with fresh, hi-octane fuel. I would like to partially restore the vehicle to operational status so that I can work on other cars. Any tips/tricks?