'98 Olds LSS, 3800 N/A. Again.
Currently my CES light is on, throwing a fairly constant P0300 random/multiple misfure and an occasional P0442 small leak in evap system. On the way home today at roughly the same time a P0442 popped up the engine stumbled badly for a second while cruising at a constant speed on the highway and the 'check oil' light came on for a few seconds. The oil level is right at the top and I've already done an ignition tune-up (wires, plugs, even coils and ignition module). Gas cap is recent and tight, and there are no obviously broken vent or vaccuum lines. According to my Carchip logger the P0300 is popping up every trip and the P0442 is only once in a blue moon.
Obvious questions: What would cause the P0442 at cruising speed, AND cause a stumble AND 'check oil' light? And what are the odds that it is related to my P0300 misfire? I suppose my next steps are to look towards the EGR and/or injectors for the misfire but that's just a baffled shot in the dark.
All of this while my ZJ is stuck in the driveway waiting for a water pump and rad. Great, just great.