My 87 IROC has Codes 42(EST) and 44(oxy sensor lean). The car's idle drops like it's going to die and then the IAC kicks in and saves it up to 900rpm then it repeats over and over. Any ideas??

 

Topless,

What is the TPS voltage at the idle position?

 

Review the internal plastic connection in the cranckshaft position sensor. Is firmly attached?. It 's broken?. It´s burned for the engine's heat?.
When was the last replace of this part? In the factory in 1987?.

Regards,

Denis V.

 

TPS voltage 0.6 and increasing to 4v WOT. Oxy sensor reading low(180-400max). I ripped off the air tube to the cat and left it open (I'm planning on a new exhaust)...would that cause a lean condition?? I figured it would be far enough downstream to affect the converter.