Ok so history, having problems with a miss, and an occasional backfire on a now completely stock camaro 1999 z28. And after switching out the ignition (2nd time for complete) resistance checked coil packs they're great, wires had went to MSD.. back to stock, same w/plugs had NGK TR's now gone, went to acdelco also now gone, and on some boshers that are 'stock' still misses. I've previously had the miss before ever venturing into ignition, which is why i started originally, only seems to be getting 'worse'. I've compression checked 1 bank (drivers side) all 150-170lbs after 6-8 cranks lol not the passenger side tho.. long story behind that but I know i could still be having a problem with motor, but i dont believe so. I've also changed the air filter, fuel filter, had a problem with temp sender changed that works fine. Not throwing any DTC's. There seems to be some smoke i've noticed comming out of the front side of the exhaust on the passengers side, perhaps where EGR hooks up?! not shore exactly.. i dont know that this could be the problem? would it miss excessively from this? Vaccum hoses were completely 'eaten' at one point replaced them all, and pcv. Used starting fluid and have gone over intake manifold etc no leaks as far as i can tell. Mass air sensor is new, Fuel pressure is also good checked it roughly 2 weeks ago. Perviously i have thrown codes for o2 sensors, i changed them with some used ones i had before i had upgraded to 'new' ones and the code has gone some time ago and never come back. Tho they are OLD o2's this could be it?... wouldnt i get another code??.. the car seems to idle fine... or perhaps not, starts sometimes at 1.2k 1k rpms and idles down to 700ish dont know if that's a true symptom but it holds idle fine dont notice the sluggishness caused by the miss perhaps it's just cuz the rpms are so low because once you rev it up in neutral or under load to about 1k it def misses... all the way through the rpms you can hear it in the exhaust and feel it. Another recent thing i decided to try was sea foam, put this in every opening the motor would allow me too. The car after seafoam ran much better, i was actually quite impressed not thinking it would do much but it didnt lessen or worsen the missing. I had another opinion on this also when i was working on it in the driveway a nieghbor told me it doesnt seem to be advancing correctly, so vaccum would be the culprit? but i swear there's no leak, I've checked over and over and over and over. perhaps im missing it? anyways WOT it seems to run fine, but then the car does have a lot of power maybe im just used to the missing 30 lost horsepower...? im open to any suggestions, or anything i may be to easily over looking, or smog related problems, not very familiar with EGR or AIR.