Chrysler Repair: 97 Chrysler Town and Country: rough starting

Question
QUESTION: I have a 97 Chrysler Town and Country, 2wd, 3.8liter. We just replaced the battery, alternator, belt, and tensioner. The very next morning my van would not stay idling to warm. I ended up having to sit in the van and hold steady pressure on the accelerator and keep the rpm's between 500 and 1000 until it was warm. Afterwards it ran fine. When I spoke to a mechanic about it he said it could be either throttle position sensor and/or coolant temp sensor. I want another opinion. Also he wasn't sure where either one of those would be located on my van. Wondering if you would have better info for me. My husband and I would like to do the work ourselves if possible especially after putting all that money into it last week for the other repairs.

ANSWER: Hi Monique,
The best approach is to get a fault code readout to see if the engine controlled has recognized the problem and logged a 4-digit code into its memory. Try the ignition switch, turning it "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window of the speedometer to see it the mileage reading changes to show a 4-digit number preceded by a P. Let me know and we'll go from there. If that approach doesn't work, then get a fault code readout, often for free, at a nationwide autoparts store such as autozone. Ask for the 4-digit number(s).
Please read the PS below and respond.
Thanks,
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi Roland, so I went to Auto Zone and got three codes from them. None of which were either of the sensors I had been told it could be. The codes r as follows. P0740, P0340, P0700. He also said it showed P0740 pending (whatever that means).??. The guy at Auto Zone said something about a torque converter.  I don't know. I'm also wondering if any of this was caused by the work that was just done on my van the previous week.

Thanks,
Monique

Answer
Hi Monique,
The 0340 code is about one of the engine sensors, specifically the camshaft position sensor. Were that beginning to fail I can imagine that the fuel injection sequencing to the individual fuel injectors (one for each cylinder) might be compromised such as to cause a rough idle. It might spontaneously self-correct or not be so significant when the engine is warm instead of cold. If the issue repeats then absent any other engine code I would be inclined to replace that sensor. It is located on the front of the engine (on the chain case cover) near the thermostat housing/top radiator hose interconnection. Remove the electoral plug on its top (lift tab to release). It has an 0-ring which may cause it to stick in its hole so tap it lightly after removing the bolt that secures it in place. Lubricate the O-ring.  The new sensor will have a paper spacer on the tip. Insert it in the hole until the tip contacts the camshaft metal surface inside, then bolt it in place while holding it in contact. Replace the electrical connector.
The 0740 is saying that the torque converter lock up (which you would notice when the vehicle speed goes past 40-45 mph as a slight decrease in rpm) is not happening. It could be the clutch or an electrical issue. The impact is a slight reduction in gas mileage but probably would not be worth investing in the repair. The 0700 merely corroborates the existence of another specific code for the trans.
Thanks for the previous rating and nomination which you are free to do again for this answer.
Roland