I didn't have any codes at all when mine was really acting up. And you won't have any codes at, even if it fails completely. What you will get is the "upshift" arrow will remain on while you are cranking the engine, and the engine won't start.
The engine degreaser should really only be tried if you have had an oil leak. I'm guessing that you probably have, because it seems like most of these cars get them over time. Your crank sensor is located behind the plastic cover that is over the harmonic balancer, (just behind your crank pulley). It is actually positioned about 1/2 way up (behind) the crank pulley on the passenger side. It is easiest to get from below, so I would strongly recommend the use of jack stands. I just made it an engine cleaning event for my car and completely cleaned the whole thing. Begin from the top of the engine and work your way down. That way you make sure that nothing is dripping down into where the crank sensor is from above. Use caution around the electrical parts of the engine too. The simply rinse it off with water from the hose. I would not recommend a pressure washer at all. That will force water into places it would not normally be bale to get to which can cause problems for you.
The plugs are not too bad to change with the exception of the #4 plug (front driver's side plug) which is a b!^@# to get to. The easiest thing to do there is to remove the upper IC tube to get to the plug. You must reseal the IC tubes when you do this. Tbird88 has some excellent re-useable gaskets for the IC tubes. Although I have not needed to remove the IC tubes yet, I don't have them, but have heard nothing but good things about them.
The symptoms you descibe makes me think that it is the crank sensor though. I have had both bad plugs and wires as well as a bad crank. Although the symptoms are similar, they are far enough different to easily tell the difference. Bad plugs and/or wires will give you a "bucking" sensation. It is quite jerky and will happen at any rpm under load. A failing crank sensor tends to begine with a "sputter" that is not nearly as violent as the plugs/wires issue. The crank sensor does not tend to show its symptoms until the car is at normal operating temps either. At least that is the way it has been with mine. And then, only at low rpms (below 2k). At higher rpms it works just fine. This is what I found to be true with my car, so it may be different with yours. I hope this info helps you though in figuring out what is wrong.