[MR2] weird MK1 problem

[BARRY S DAVIES]

This one is strange.
symptoms started as the engine seeming to intermittently rev limit itself at about 5k. That got progresively more frequent. Then one day it completely quit running and I ended up towing it back home for analysis.
 
This is its current symptoms
It will start and run fine, accelerating hard and with no loss of power up to redline. It will happily drive for about five minutes, then the check engine light will briefly flash, and it will lose power. It may pick up again a couple of times, but it will soon die.
 
After it dies, when the ignition is turned on, the check engine light does not light as it should before starting the engine. The engine will crank but not fire. There is spark.
The other really strange thing is, the fuel pump is running continuously when in this state. Seeing as how the fuel pump circuit is disabled by the contact in the AFM when the engine is not running, I cant see how this can happen. (AFM extends a ground to the Circuit Opening Relay when the engine is running). Maybe the COR is stuck closed, but that wouldnt cause the engine to die.
 
Once it is dead, it will restart after leaving it alone for a couple of minutes. Then it will repeat the cycle, but will not run as long.
I thought that the ECU was getting itself in a locked up state. Changing the ECU had no effect.
 
Battery voltage was low too, (probably from all the cranking). Swapped the battery for a new one, same problem.
 
I am wondering if the alternator is generating some spikes which zap the ECU. 
 
After its five minutes recovery time and it decides to play nice again, the check engine light is lit as per normal when turning on the ignition. 
(This is how I can tell it just recovered from its "state"). I can then check for diagnostic codes, but there never are any.
 
My next step will be to back probe the ECU while it is in this state and see if there are any anomalies.
Anyone got any bright ideas? 
 
cheers
Barry