Why?

I thought all my car problems were solved. Until today.

After fixing a piece for the brake assembly on my car after trying to replace a wheel stud, i told my dad that the car still seemed to run rough. His hunch was that the timing and mixture was way off, so he called Pep Boys to find out if they could tune up the car. They could, and my dad decided to drop it off at around six and leave it overnight. This was at around two o'clock. So I decided to drive over to Circuit City (DVD sale!!!), and Valu Thrift (found a front-loader NES for 1.99). When I got back, my dad decided to do a compression check for shits and giggles, even though he didn;t think it would reveal any problems.

So he pulls spark plug number one. It's clean. Pull plug number two. Fouled, dark black, smells like gas (when we changed the plugs when we first got the car, plugs two and three were fouled, we assumed since the wires were resting on the manifold and had melted partway through). Pull plug three. Somewhat fouled, but not as bad as number three. Pull plug four. Clean as a whistle.

So lets start the compression test.

Cylinder one: 180. Good.
Cylinder two: 70. Damn. (at this point I guessed three would be at 120)
Cylinder three: 110. Shit.
Cylinder four: 180.

So basically, my car is running on three cylinders. My dad thinks one of three things is wrong: bad head gasket, bad rings, or bad valves, and he's leaning towards the latter.

"All it needs is a set of plugs and wires" they told us at the dealership.