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First post here, definitely glad I found this place!
I've got a '92 olds 88 with a series 1 in it, about 199k miles on her now.

Start up great, runs great for a about a minute, and then begin the problems.

Starts missing at low rpms at about 25% throttle or more. Cruises fine at all speeds, and accelerating gently it runs virtually perfect, but under medium acceleration, especially from a dead stop, it's missing and backfiring. Sounds like a backfire into the intake to me at least, can't get it to do it while I'm under the hood... Nice pop though, more than a knock. It also does a little knocking when it's "spazzing out" though. It seems to be an on/off problem, rather then one that comes about in a linear fashion, which seems to rule out a mechanical issue.. MAF, TPS, Temp sensor, plugs, wires, fuel filter, air filter, and o2 sensor are new. I found a coil pack to be failing, and replaced it, but the problems remain. (Delco ign, BTW) Injectors all impedance test OK. All the sensors mentioned have clean connectors. IAT has been cleaned... I'm gonna compression check soon just to be sure no valve seat or ring problems..

Now... When I unhooked the 02 sensor, the ecm didn't notice. I even drove it around without it and it drove the same... And the old one (very caked) had to be toasted, and replacing it made no difference. At all... But more interestingly, even after restarting and driving it again with no 02 sensor, the ecm never threw a light OR a code... It still notices every other sensor I've checked...

Sorry for writing a book, but I'm pretty stumped right now... Advice MUCH appreciated!
 
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