2008 Grand Caravan SXT with 3.8L V6 (~180k). When coming to a stop after any period of higher speed driving (60mph+), the van starts to shake/shudder, acting like it wants to stall. I've noticed the idle speed drops to around 600 rpm (normally between 800-900). Sometimes it's not too bad and I can just hold the brake pedal until we go again. Sometimes it's so bad that I have to shift it into neutral, and then do a neutral-drop to get it to go without stalling. No check engine lights (we have an EVAP code that shows up once in a while, but I don't think that could be related) and it does not do it around town. So far I've changed: plugs/wires/coil pack, intake manifold gaskets (upper and lower), pcv valve, and I've cleaned the throttle body numerous times. I was wondering if it could be the IAC valve, but I do not see a way to access it on this model. I have not done a compression test, but I think I will do that this week. I'm worried that the torque converter is bad, especially since everything is fine when the van is put into neutral. Any thoughts are appreciated.
PB

 

I thought about the things that happen when you leave a highway. You have a lot of heat after a highway drive so more resistance in your electrical such as the things you have changed.
So what isn't so obvious is that the radiator fan kicks on. And if it has 180k that motor might be shot and pulling way more amps than it used too.

Let your van sit in the drive and warm up until the fan kicks on, if the fan kicks on and the vehicle tries to die you have 1. a bad fan or 2. a weak alternator, or bad regulator on the alternator.

If you have a multimeter and you know what you are doing with it you can test the draw of the fan when it kicks on and check the internet for the spec power draw.

You can't use the A/C to test this theory because the computer ups the RPM to compensate for the A/C and would mask the excess fan draw.

 

Seem like the torque converter clutch isn't fully disengaging after coming off the highway. The torque converter has a clutch that is engaged in 3rd or 4th gear once the rpm reach 2000 to eliminate torque converter slippage to give better fuel economy. If the torque converter clutch isn't fully disengaging after highway speeds it isn't allowing the proper slippage of the torque converter needed under normal slow traffic and stopping situations causing engine hesitation and stalling. I'd start with checking proper operation of the transmission control solenoid pack.

 

So last night when getting off the freeway after an hour-long highway drive, I decided to use the manual shift (auto-stick?) to downshift. Made it to the light and had no problem. I did take a longer time to slow down, but I think either way its leading me to think it's transmission related. I will still probably check the other things (compression, fan amp draw, etc...) but I think I will focus my attention right now on the trans, and making sure the solenoid is working properly before I decide to pull the trans out and replace the converter. However, there are not any check engine lights (related to the transmission at least). Would there be a trouble code with the solenoid going bad?

 

Usually torque converter issues will give you an error code it might need an advance scan tool like the dealer or an reputable auto repair shop to read it from the TCM. The reason I believe it transmission related is that in your post you said sometime you needed to put the trans in neutral if it was cause by anything else the issue would still there with the transmission disengaged. Plus you manually downshifting the transmission would take the converter out of lock up another indication it's transmission related. Is your transmission fluid dirty you might want to try changing the transmission fluid and filter and if you do I'd put in a 10 oz bottle of Lubeguard Platinum with the fluid. You might want to consider trying that first if you have some miles on the trans fluid.

 

We had the transmission rebuilt a couple of years ago. I think I will probably change the fluid/filter and see if there is anything in the pan.

 

Well, my wife wanted to take it in to the same people that rebuilt it a couple of years ago. Apparently it's time for another rebuild. This will be the second rebuild in the few years that we've owned this. Sucks...

 

Go for a second opinion at reputable transmission shop most of them will give you a free estimate on repair. Usually when these transmission goes they slip and whine because the clutch debris clogs the filter sometime so bad the van won't move. Usually when the engine stall at a stop it's likely the TCC solenoid in transmission solenoid pack. How well do you know this transmission guy good reputable shops usually warranty their work parts plus labor for the first year then parts only for the second year. It's rare that most rebuilt won't last longer than the original transmission this guy sound like shyster to me.

 

We're just going to go with it. They're going to install a trans cooler also which should help keep the fluid from burning (apparently the 62te is prone to overheating). They're giving us a decent price, and hopefully we'll have it back by the end of the week. Plus they do have a one year warranty. Next time I'm just going to go for it and rebuild the trans myself, although I hope there isn't a next time.

 

Well unless your hauling heavy loads or a trailer there should be any need for a trans cooler the build in one should suffice. I know this guy who run an intercity air cargo courier service for years and he always bought Dodge Grand Caravans because of their price and being economical to run plus it's a nice riding highway vehicle. Right now he running a 2012 GC Crew with Sto N Go he has approx 585,000 km he got the transmission rebuilt at 425,000 km he services his van as a severe use vehicle and it's very well maintain he never had issues with the trans overheating with regular trans condenser. Right now he looking to get a 2020 GC since it's their last year of production possibly a left over in the fall he said that should last him 10 years long enough to take him to retirement. The thing is the guy who rebuilt your transmission last did he take the time to flush out the trans cooler lines before installing your rebuild transmission if not he contaminated the rebuilt unit with debris from your old failed unit that would explain why his jobs didn't last..