JGheen, it sounds like your truck ran better than ours (mine anyway) when stock or close to it. I haven't done the GSK or a plate yet but plan on it.
Having an automatic and 4. 10s our truck will just flat out quit making power about 2600 RPM or so, if your in 3rd it won't shift to 4th because your road speed is too low for the PCM, it just lays there, won't accelerate, won't shift, won't do crap, just sound like it's trying to lay a big turd. Once you lift off the throttle, let it shift, life gets good again. It may red line at 2900 but the only way mine is gonna see it is on vitamin "E".
Having a 1st gen, this 12V and a 24V; I would say the drivability of this truck is the least enjoyable of all of 'em. A big laboring pig actually, a hearty bump in pump timing kept me from having to go to therapy anyway.
There seems to be a lot of difference from one truck to another and it sounds like your's was good from the get go.
Wayne