Pulled a code 300 "random/multiple misfire detected" on my '96 WS6 today. I had about 4 gallons of fuel in the tank last week which dated back to October. Filled the tank with fresh fuel. Cruising today brought up the code, although I admit that the Pontiac hasn't been running too smooth for the last 500 miles.
I did a scan and monitor with Auto Xray and came up with the following:
Fuel System 1 & 2 - Closed Loop
Load Value 2.7%
Coolent Temp. 222 degrees
Short Term Fuel Trim 1 2.3%
Long Term Fuel Trim 1 -1.6%
Short Term Fuel Trim 2 0.7%
Long Term Fuel Trim 2 2.3%
MAP Sensor 9 in. hg
Engine RPM 771
Vehicle Speed 0 MPH
Ignition Timing Adv -21.0 degrees
Intake Air Temp 123 degrees
Air Flow Rate .64 lb/min.
Throttle Position 1%
Atmosphere Off
O2 Sensor 1 Bank 1 .090V
Short Term Fuel Trim 1 -1.0%
O2 Sensor 2 Bank 1 0.070 V
Short Term Fuel Trim 2 Not Supported
O2 Sensor 1 Bank 2 0.080V
Short Term Fuel Trim 1 0.0%
O2 Sensor 2 Bank 2 .715V
Short Term Fuel Trim 2 Not Supported
In addition I received "Sensor not ready" on O2 #2 & #4 when doing an oxygen test.