American Motors: Fuel Injection, trouble shooting guide, rich mixture

Question
Hello I have a 83 Alliance with only 22K miles on it but it has a problem.

It has a throttle body fuel injection setup and is running WAY to rich, so much that it wont run other than to idle it. Indications are thick black soot out the exhaust and the air filter gets soaked with fuel. ALso the engine backfires through the throttle body. Ive read the chilton book and performed the basic tests and it has not helped. Basically something is telling the injector to pump in too much fuel.

From the trouble shooting guide it suggested to change the Oxygen sensor on the exhaust which I did and no improvement. Getting the trouble code out of the ECU is a 3 which indicates a bad wide open throttle switch and or closed (idele) throttle switch which of course the book doesnt tell how to test either.

One thing I have observed, while its running for its brief time before stalling from flooding out there appears to be a leak at a gasket between the intake manifold and the throttle body lower base, can this cause this symptom?

So any suggestions are greatly appreciated. Its a car for my son and even though its 22 years old its like new if I could fix this problem.

Answer
Throttle body leak probably makes the car run lean and the compuyer sensors keep trying to richen the mixture.  When the engine RPM increases the percentage of leaking air is less but the the extra rich mixture floods out the engine.

I would try to replace the gasket and check for other vaccum leaks to see if it resolves the problem.  Remember to change the oil because it is probably fouled & thinned from fuel washing into the crankcase.