Wheels require balancing.
Might just need a front end alignment or maybe balance and rotate your tires.
Bad tires, out of balance , wrong wheels , bad tie rod end.
Probably wheel balance.
worn front end bushings, the death wobble usually needs track bar bushings but I recommend replacing them all with nylon when you do it.
problem with your transmission in 5th gear
The fact that it's a piece of junk chevy, get a mustang. Ford all day.
Tires out of balance, bent wheel, or defective tire.
Most commonly, this problem is due to a out-of-round tire or a tire that needs a rebalance.
Worn steering parts, worn suspension parts, tires out of balance, out of alignment,
Mine did the same thing. It would get better when I got up to 50+. Turned out to be the CV joint. Replaced the whole axle for around $80(part only).
Tire our of balance or bent wheel. Have your tires rotated and balanced.
Tire out of balance, bent wheel, defective tire, worn suspension or steering parts. Have the tires balanced, and all parts inspected.