Alright, after fooling around a ton with my Z28, and with help from you guys (especially SweetRed95TA) I determinded that false knock was retarding my timing emensely and causing my car to run like crap.

All in all, I downloaded TunerCATs, got the ECM file I needed, and set max spark knock retard to 0 for all RPMs and for all MAP readings. This solved 90% of my problem. Now, instead of terrible cutting out at random RPMs, it's studdering slightly (but noticably) at high rpms, 5500+usually... I haven't had a chance to re-log the PCM and examine the tables, but is it possible that my timing is still getting knocked down? I zero'd all the tables so theoretically it should elimnate it all, right?

Basic information: 1994 Z28, 133k miles, A4. 4k miles on plugs, wires, and MSD ignition coil. Fresh tranny fluid in the pan, fresh trans filter. New fuel filter, 91 octane. Recently seafoamed oil, fuel, and through brake booster. (about 1k miles ago), STP fuel injector cleaner in the tank right now. I guess that's about it, any help would be greatly appreciated. Thanks!