I bought my blazer in 2008, from the dealership, the gas gauge did not work.
The first big investment was the intake gasket that went bad.
It was replaced with a metal gasket, and shouldn't need replacing ever again.
After that, it started acting very strangely...it would be going down the road, and start hesitating, or lose power suddenly.
I went through and replaced plugs, wires, distributer cap and rotor, air filter, gas filter, battery, cat, and exhaust, the fuel pump sounds like it's screaming, it gets terrible gas mileage, and the front dash squeaks.
So far to fix the hesitation issue, i've dumbed a bottle of sea foam in the gas tank, which has helped for now.