okay, so here is the update.
It no longer misses, it only missed like once or twice in the beginning of the problem but hasn't since. found out the "popping" noise was the engine backfiring. sounds like unburned fuel igniting in the exhaust manifold.
I had the fuel injectors serviced to specs at a specialized shop. didn't help. cleaned the intake plenum and the gunk, didn't help. changed a couple vacuum lines (the ones to the weird black mystery ball attached to the hood) helped for a few days but same problem gradually came back. checked the fuel pressure, its within specs according to my Haynes manual.
I changed the crankshaft position sensor and its been a week and a half (about 15 key cycles of decent trips) and the computer still has not learned it. the code comes back right away after cleared. thinking of replacing TPS next, or even coil packs. probly coil packs first. any other ideas?