Why does a 1984 Corvette feed much to much gas into the intake if the engine check light is not on but when the light is on run normally?

When the lite is on the engine runs on a set of specs. When itis off, the computer controls the mixture. Have the codes read and repair what is causing the light. Does this seem to happen at different times? Does it seem to happen when you attempt to start the car after it has reached operating temp? Does it just happen when youslow or stop for a light and stall the engine? If you say yes to any of these questions, it may be the cold start sensor. This was a pretty common problem when the car first came out and had GM baffled for a while. Replace the sensor and it should fix the problem. The sensor acts like a choke whencold, giving a rich fuel mixture for cold start. When it goes bad, it gets confused and will give a rich mixture after the engine comes to operating temp and flood the engine. To start a flooded engine, take off the top of the air cleaner, unplug the injectors, start the engine and burn out the fuel. Just before the engine stalls, plug in the injectors and the computer will reset for a while and the car will run fine until next time the sensor gets confused.