99 Pesky 1391 Code

So my check engine light came on several weeks ago and after reading the 1391 code, I thought I'd get lucky by changing the cam and crakshaft position sensors. What can I say, I'm a gambling man. Before that, the light would go out intermittently and come back on. When it was on, especially at highway speeds, the car would hesitate.

Thought it might be a loose gas cap because it seemed to make a difference when I fueled up. The light would go out after a few minutes. Changed the gas cap.....strike 2.

What I have realized to this point is I can pretty much tell when the CE light is going to come on because the car will take a few extra seconds of cranking to start. Car has 75,000 miles, gets Mobil 1 every 3,000 and runs fine otherwise.

Any thoughts? Timing chain, fuel pump, fetzer valve... whadda ya got?

OK. I gaffed. I am actually getting the 1684 and 340 codes as well. Gotta be the camshaft sensor 'cept I already replaced that. Could it be the wiring for the sensor plug? The ECM? What's the dillio? Help!