'95 SC Riv - lots of errors

I have a '95 supercharged Riv that has a number of error codes popping up. The first sign of trouble was probably a couple of years ago or so when I noticed that the Traction Off light would come on every once in a while. Then a couple of months ago it morphed into the Service Engine Soon light along with diagnostic codes P0321 (Ignition System 18X Interrupts) and P0361 (Ignition System Elec Spark Timing EST Not Toggling). This came and went for a while, but for the most part the car ran fine. Sometimes the engine would be a little erratic, but it was fairly temporary.
In the last few days though I am getting a host of indications and error codes. They are as follows:

Dash Indicators:

Service Engine Soon
Traction Off
Check Oil Level
Low Coolant Level
ABS

The Low Coolant Level and Check Oil Level indicators come and go together. I found that they will go on and off in response to the gas pedal so long as I was going over 50 or so. Giving it gas would make these two indicators go away while letting up on the gas would make them come back on (at least I think it was that way - it could have been just the opposite).

While the car is in this failure mode the Electronic Climate Control and the Cruise Control do not even power up. I could stop the car, turn it off, and restart it and sometimes that would fix it for a while, but it would always come back at some point. Also in this failure mode the car would oftentimes run very bad. When starting from a stop the engine would rev, but the car would only slowly start to move similar to how it would be if the transmission were slipping really bad (my tranny was rebuilt less than 2 years ago, so I think it is fine (besides - it only does that when I have these crazy intermittent indicators).

I had the codes read again today at the auto parts store and here is what popped up:

Current Codes:

P0571 ABS Traction Control PWM Signal Problem
P0640 Quad Driver Module QDM 1 Fault
P0670 Quad Driver Module QDM 4 Fault


History Codes:

P0321 Ignition System Problem 18X Interrupts Lost Signal
P0361 Ignition System Problem Elec Spark Timing EST Not Toggling
P0406 Linear EGR Pintle Position Error
P0571 ABS Traction Control PWM Signal Problem
P0640 Quad Driver Module QDM 1 Fault
P0650 Quad Driver Module QDM 2 Fault
P0670 Quad Driver Module QDM 4 Fault
P0705 PRNDL Switch Failure

My first instincts are the computer, but I really do not know. Anyone have this trouble before?
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http://ucfpics.com/95Riv.htm

My first instincts are the computer, but I really do not know. Anyone have this trouble before?
Yes, and it is time to commit your PCM to the “funny farm”! I have seen this many times, and when you have that many quad driver faults, the transmission will not only shift unpredictably, but also start in second or third gear. You may also need a new CKPS and some EGR cleaning, but I would change the PCM first.

The Riv is finally back up and running. I tried two different refurbished ECM's (PCM) from the auto parts store to no avail. Same error codes.
I was going out of town for the holidays, so I left the car with the dealer. They fixed it. Turned out to be a bad ignition switch. Not cheap though. $230.00 for the switch. $552.00 overall.