Chrysler Repair: Pulling Hair Out !, fuel air mixture, 1996 plymouth breeze

Question
Hi Roland,
 I have a 1996 Plymouth Breeze. The problem is it was stalling at idle speed i.e., at stop signs and lights, plus the check engine light is on. Then it wouldn't start at all without keeping the gas pedal down. As soon as I let off the gas pedal, it stalled. I took it to autozone and got a code 1390. That is timing belt skipped a tooth. Well the timing belt was replaced, the downstream O2 sensor, crank position sensor, plugs, wireswere all replaced too. The upstream O2 sensor is less then 1 years old. After my mechanic friend changed the timing belt, there was no change, and it still ran the same. BUT when he disconnected the positive battery cable, the computer was reset and now it runs fine again. Well I ran it and the check engine light came back on and now its back to where it was--won't start without hammering the gas pedal then quits as soon as I release the gas pedal. On board diagnostics say O2 sensor is detecting a rich fuel/air mixture, but nothing else. Any ideas?

Answer
Hi Mark,
I am not knowledgeable about which engine you would have in that '96 Breeze, as I have focussed on the 85-95 models. I believe a new engine came in around that time which operates without a distributor, etc. so I am only able to make one suggestion to you. If it is a thottle body located single fuel injector type of FI system, then I would suggest that you take a look at the spray pattern of behavior of the fuel injector which should be visible in the throat of the throttle body. It may be that the injector is faulty in that it is leaking gas beyond what the engine controller is asking for, and so you have too rich a mixture. This might be evident in the form of dripping from the injector after the engine dies, or a spray pattern of fuel on the butterfly which is very uneven when the engine is mainainted by means of the throttle valve stomping. If it is a multi-point (several injectors) then this analysis may not be applicable. You could also remove a spark plug to see if its look like it is wet with excess fuel (which is what the trouble code is saying is the case) to corroborate the fault code accuracy.
I had a similar problem on my 2.5L 4 cyl '89, and it was due to an injector that had started to leak as I have described.
Roland