Engine Mechanical problem
1997 Dodge Caravan 6 cyl Front Wheel Drive Automatic 173000 miles

3.3liter v-6 4sp trans has an intemittent and inconsistent idle problem. Vehicle runs smoothly at speed but when coming down to idle it will shut down. This seems to have gotten worse as the temp has dropped to around 40 degrees. I have replaced the battery, the negative post terminal, the idle air motor and the pcv valve and breather hoses. The egr valve is only 6 months old. The fuel pressure is within spec even when the idle is registering only aroun 400 rpms. The problem went away alost completely after replacing the throttle pos sensor and map sensor with clean used parts. I can find no evidence of vacuum leaks. The fuel filter is also new and I have tried various fuel treatments in case of water contamination. I get no codes from the PCM at all. Sometimes putting the vehicle in park rather than neutral when restarting will remedy the situation. I can reliueve the fault by modulating the gas and brake at a stop. Also on restart the system seems to act like it is loading up (similar to old carburetors).

I have a good knowledge of the vehicle dynamics and repair plus a haynes manual to assist but cannot figure out the problem. My local mechanic is also stumped, although he lacks the diagnostic tools to further assist me.

Does it only do this after going about 45mph+? in other words, will it only stall if you slow down after being in OD? sometimes the torque converter clutch solenoid can keep it locked up when you slow down and it can kill the motor

It is usually after having been on the interstate but after that will happen more often in town. Should I try driving it in 3sp mode and see if the problem changes?

wouldnt hurt to eliminate the possibility of a trans issue.