Chrysler Repair: Voyager 1995: does not start, or jerky after warmup, air fuel mixture, oxygen sensor

Question
Dear Sir,
I have voyager 1995 V6 3.0L. I have read some similar posts in this forum but not quite the same.  one time in the morning I could not start it (no sign before). I thought it was battery, but not (after testing it at Autozone). when I jumped with other car, it started after many tries.  another day, this came again, and could started with jumping and more tries. I was tired with the jumping way, and I could not start again without jumping. finally it was towed to shop for repair.  the mechanis said it was PCM problem.
Is it right PCM dies without prior indication?
Ok, then it has been replaced with new PCM.  one day after the change, this car start jerking. it sart easily in the morning when cold but it only runs in 5-10 minutes.  I cannot start again unless I keep pushing the gas paddle little bit.  when I release the gas, the enginee dies. changing all sparkplug, air filter, oxygen sensor do not help.   
Now I return it back to the shop (still there). the mechanic said it may be distributor.

please give some answer, clues or suggestion on the problem. is it PCM and distributor at same time? or anything else.
every help is greatly appreciated.
Sincerely
Sugeng Triyono

Answer
Hi Sugeng,
I doubt it is the distributor but in any case it is easy to check that theory using the on-board diagnostics. Just turn the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light which will remain "on" to begin to flash, pause, flash, etc.  Count the number of flashes before each pause. Then repeat to get the count accurately. Then combine the number in pairs in the order they appeared to form two-digit numbers. The last should be 55 which means "end of readout". The other numbers are clues as to what is wrong. Only if you got an 11 or a 54 would there be a problem with the distributor.
I suspect that you have a problem with the air/fuel mixture not adjusting with the warming up of the engine, or with a valve that is diluting the mixture. Specifically, the engine coolant temp sensor located next to the thermostat housing on the top of the engine (where the top radiator hose attaches) has to change resistance as the engine warms. It has two wires. You gently lift a tab on the edge of the plug to remove it. Then measure with an ohmmeter the resistance between the two pins. It should be 7,000 to 13,000 ohms when the engine is cold, and 700-1000 ohms when the temp is at 200F (half scale). If it isn't dropping down when the engine warms the mixture will be too rich.
On the other hand there is an exhaust gas recirculation valve in a pipe that runs between the exhaust manifold and the intake manifold which feeds some exhaust gas back into the engine when you are driving along. But when you coast or idle it has to close. It can get gummed up and stick ajar rather than close; then you get a too lean mixture. So find the valve and check the valve stem which is an opening between the valve body and the round vacuum actuator and has a circumferential slot. Use the tip of a screwdriver in the slot to test that the valve is moving freely and closing via the return spring to a fully seated position. If not spray some WD-40 on the valve stem where it enters the valve body.
Other fault codes that come from the readout may also give a clue as to what is wrong.
So I would ask the mechanic to read out the fault codes and go by those numbers. Write back if he doesn't know or go to www.allpar.com/fix/codes.html for a fault code table. I would not blame the distributor sensors unless you get a code 11 or 54. Then you just replace the sensor unit, not the whole distributor if needed. And check whether the coolant temp sensor is changing resistance down to 700-1000 ohms when the engine is warmed up.
The PCM is a rugged and reliable module. They do fail, but not that often. I would like to know on what basis that was changed, and whether anything else was changed that might have been the principal reason that it starts better now?
There is a fault code that would show if the PCM had failed, 53, so unless he read the codes and got a 53 he shouldn't have replaced it.
I wonder if you have a mechanic who likes to 'throw parts' at the car to try and make it work rather than doing the proper diagnosis.
Those are my suggestions.
Roland