Chrysler Repair: 2002 Town & Country Stall, lever point, flat blade

Question
2002 Chrysler van (3.8l) 150,000 miles. No error codes. Clean throttle body, new fuel filter, good fuel pressure, new wires and plugs.

Car intermittantly stalls when I let off the gas. For example: Car is idling at 750 rpm. Give some gas (say to 100 rpm). Let off gas. Van either returns to idle or (this is the problem) bogs down to about 500 rpm before recovering or stalling.

It also seems that the car is missing right around 50 mph and it doesn't start as automatically as it used to.

Other than the above, it idles great, runs great, and has good power.

Thanks!

Answer
Hello Frederick,
In the absence of codes and with the transitory and particular behavior of this stall one has to fall back on fundamentals. Chances are better that it has to do with the fuel/air ratio (mixture), though missing at higher speed could be related to the spark system (but you appear to have replaced most of that except for the coil package).
It is my hunch that what may be causing your problem is a partially obstructed or failure to close tightly egr valve. If you haven't taken a look at the motion of the valve stem in the cage area of the valve when you rev the engine I would urge you to do that. There is a slot in the stem that improves visualization and also you can use that as a lever point to move the valve manually with a flat blade screwdriver.  You might try spraying some penetrating oil at the base of the stem where it enters the valve to improve the responsiveness of the valve. The next step would be to remove the valve and inspect the valve and its seat for the build up of exhaust condensate and possibly to clean it out by hand. That to me would be the place to check first.
Let me know if this suggestion bears and fruit, and if not, whether you find another explanation.
Roland