Join Date: Mar 2002
Location: Austin, TX, USA
That car should have an OBDII compliant engine controller on it. One thing about OBDII is the codes are more dependable that the 1980-1996 controllers. Get a cheap hanes manual or even chilton. They should have a sensor diagnosis tree in there that will allow you to check the MAP, O2 sensor, and anything else you suspect might be contributing.
Based on the codes it sounds like the ECM fattened the mixture enough that the engine should have burned rich, but the O2 sensor told it was lean. By the way, lean means high O2 sensor voltage. Try grouding the O2 sensor input to see if it has any affect. It's highly probable that, fuel pressure, injector issue, MAP sensor problems, or an exhaust leak could cause an abnormally lean reading.
What do the plugs say? If they are black with soot, then the computer don't know WTF is going on.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI