I have a 1995 Cavalier with 145,000 Miles on it.
About 2-3 weeks ago, it started hesitating HORRIBLY.
It did leak a lot of antifreeze, and oil.
I tore it apart, and replaced the head gasket, valve cover gasket. Cleaned out the intake manifold, cleaned the head up. Did some other work, general cleaning, replaced all the gasket's ect. I used a FelPro Permadry head gasket set.
Upon starting it the first time, it ran great! I turned it off, started it again, and it was hesitating. Even at idle. (This is the same problem prior to changing the head gasket). I started checking the sensors while it was running, I unplugged the Map sensor, it ran good again. Then it started hesitating, yet again, so I replaced the map sensor. Still, same problem.
I started unplugging the fuel injectors, I got to one of them, and the engine didn't change in performance (with the others, the engine stalled). So, I knew that one of the fuel injectors was bad.
I just replaced it. It ran great! Good acceleration, everything!
I came back home, turned the car off. Then went to run some errands, and it started hesitating again.
If I push the gas pedal slightly, it will accelerate without hesitation, but if I push it just a little bit more, it will hesitate like crazy. I already know the one-way valve in my fuel pump is bad, because I have to start it, I have to turn the key for about 10 seconds.
But now I am thinking my fuel pump has just totally took a crap.
Any other suggestions that may be easier (and cheaper) to fix? Because my fuel pump is located inside my gas tank. And a replacement costs near $300.