bought a '90 full size blazer a few weeks ago, started and idled ok but on the way home really low on power at highway speed.
Idle RPM seemed to jump around a bit so changed IAC, while doing that decided to check cap and rotor, realized screws that hold cap on were stripped and cap could not be tightened. replaced distributor with Davis Unified distributor from Summit. Also was throwing code 43, so began looking at knock sensor, it was physically damaged where harness connects to it. Replaced and reconnected it. I think that took care of my my code 43 check engine light didn't come on during test drive afterwards. Power is still terrible on highway though, seems ok, but not great on surface roads, most likely due to it being geared to high, it has 35"s on it at the moment and I know it hasn't been regeared, cause speedo is off like 7 mph on the highway. With tranny in 3rd gear though on highway it wont get out of it's on way. Hardly keep up speed going up a small hill over an overpass. I know to ever be right I'll be getting gears replaced sooner rather than later, but any ideas on why it seems so lethargic on the highway? I really thought it felt like the timing was being retarded so bad due to the knock sensor that replacing that might make a big difference but doesn't really seem to of helped at all on that front.

I appreciate any advice ya'll might have, kind of scratching my head with where to go from here. I haven't checked compression or anything, but it starts and idles so smooth that I don't "think" it's any real internal issue.. maybe so though