have a code 42, the o2 sensor drops voltge slowly to 0, then my iac stays either wide open or completely shut. the comuter compensates by dumping in 44% fuel and drowns the cyinders. Was running a 305tpi ecm wit a 350tpi hypertech chip, tried putting in a 350tpi stock prom, wouldnt start. Bought a 350tpi ecm the prom still wouldnt work. Works the same with the hypertech so it could be the chip thats killing it. But wat else could be causing the mayhem?