Maxima 1995: OCCASIONNALLY hiccups, OCCASIONNALLY stops while idling

This is an intermittent problem about which I posted a message on 
September 3rd.

The car starts easily at any temperature, even on a very cold Qu‚bec 
winter.  It runs smoothly, well almost always...
 
Very seldom, it hiccups for a second or two while I drive at regular 
speed: the inertia restarts the engine.
 
More frequently, but not very frequently, it stalls while the engine 
is idling.  Then I have to use the starter for 10 to 30 seconds before
the engine restarts.  When it does, I smell a very strong unburned 
fuel odour in the car.  Although I have no absolute proof, I suspect 
the fuel comes from the exhaust pipe, since I have not seen any fuel 
leak.
 
In September, I thought that the Engine Control Module cut both the 
ignition and the fuel... I was wrong: it cuts the ignition only.
   
I just reread the Engine Control Module OBD II codes; I got two.
 
One, P0115 is related to the Engine Coolant Temperature Sensor 
Circuit.  I am prone 
to discount it because the problem occurs at any engine or ambient 
temperature.
 
The other, OBD II P0136, is related to the O2 Circuit (Bank 1, Sensor 
2).
The Freeze Frame Data is:
	Fuel System 1  Closed Loop
	Fuel System 2  Closed Loop
 
This latter code is different from the one I got in September, P1355 
related to the Crankshaft Position Sensor Reference.

I am afraid it will be difficult to find because the problem occurs so
infrequently.
 
 
I thank you very much in advance for any help.  

-- 
Jean Castonguay
�lectrocommande Pascal