MAP Sensor

My 1990 cutlass supreme 3.1 is dying and throwing code 33 and the code that says lean fuel, when in drive, if you are driving and you let off the accelerator, it stays constant like cruise control is on. its not on. I suspect a vacuum leak, but i need the Vacuum diagrams.

No under hood label with the emissions diagram?

you can check your map sensor and see what the voltage is see if it is getting 5 volts and a voltage drop across the sensor. i had a similar trouble shooting problem with a plymouth breeze with the same conditions as you. does the car have a really rough idle also? an easy painless way to check for a vacuum leak is using hair spray and listen for the engine cut out.

might want to replace the O2 sensor. I know that fixed a lean problem on my 1990 STE 3.1.