jemezbob

OK, so, for the past two years, my 1996/97 truck has had this persistent problem of the engine light coming on. The light is accompanied by a surging while I'm driving that has feels like the truck's running out of gas. At times, the surging has progressed to the truck stalling when at lower speeds and/or stopped.
The code that continues to be associated with the "service enging soon" light is P1320 - Primary Ignition Signal Fault. When one of my three mechanics has run diagnostics on this code (including the dealer), the response is that there's a problem with the distributor.
Well, I'm on my third distributor (this third one was covered by the warranty of the second installed over a year ago), so, I feel confident the distributor is not the problem.
I also replaced the EGR tubes and advanced the timing (based on a thread I found here that seemed to describe a similar problem described by 1997XETruck back in August 2003).
I've also replaced a cracked manifold, upstream and downstream oxygen sensors, and an evap canister/switch/O-rings.
So, it seems that what's left is either the ECM/computer or the wiring connecting the computer to the distributor. My local mechanic tells me that if the computer was faulty, he wouldn't be able to communicate with it (plus, I don't want to have to drop over $500 on another part, not including labor). I'm hoping the wiring will fix it.
Any suggestions? Anyone have a wiring chart handy? Anyone know where in particular I should be looking to fix this problem?
I bought this truck because my last Nissan was a champ. This one has been little more than a money pit.
Please help!
jemezbob