2005 Pacifica 3.5L - Transmission maybe?
 

Hi all, new to the site. I have a 2005 Chrysler Pacifica Touring 3.5L with 169,100 miles. Have had it since 2010 and 99k, only 1 previous owner in FL. I'm in Pennsylvania. Like many of you, we experienced the seemingly contagious failing motor mounts, and the infamous about-to-drop-an-entire-engine-on-the-highway engine cradle. Spent 2k in 2012 on new motor mounts and oil pan. Always changed oil on time and have done my best with putting the recommended 89 octane fuel in(during gas spikes, 87 was non-negotiable). Earlier this year, I hit a pothole so fierce that my passenger front strut flew RIGHT UP THROUGH THE HOOD leaving a bullet like hole and a subsequently damaged suspension. Insurance took the claim and replaced hood and shock/strut assemblies, and for god knows what reason, blamed the rotting cradle on the event? and thus spent 3 weeks and 3 grand putting a brand new cradle on the vehicle. We then paid to also replace all tie rod ends, sway bar links and relative bushings. Also had first throttle body and fuel injection services under our ownership at 151k. She has truly been a champ, I mean I'll be honest. Im not a slow driver and drive primarily highway miles at 75mph+. Ive never had a check engine light or really any of the debilitating problems everyone seems to encounter, but I fear the possibility is on the horizon. Only since about 165k, pacifica has begun to 'jump' when switching gears occasionally(a startling jump, too) and am running into a full engine roar when I depress the gas shortly after braking, but am getting a hiccup and an embarrassing turtle crawl back up to speed where that roar was typically met with solid acceleration. And its not an unreasonable expectation being how long she so reliably lunged ahead in identical circumstances before. Is my transmission about to completely die, or is it a fuel delivery issue maybe? Again, no dash lights now and never previously. Everything else is still smooth, and my mechanic of many years seems to think Im crazy. Maybe its just the point in time where an engine of this age can't perform as it once did? If that's the case, any one have recommended options for packing some punch back into it? A remanuf long block is 5k, and new transmission and required water pump replacement is half of that, so before I even considered doing something of that magnitude Id love to hear from others. I have put so much into a vehicle that has given back so much for so long(and not to mention is the only car I can insure with full collision/comprehensive/rental the whole 9 yards for 78$/mo). Call me crazy, but I'm willing to take on whatever can prevent me from ending up with a dead car and nothing to show for it because dead Pacificas are widely available in my area, and will see me to maybe 400$. Also, Im curious if anyone has any theories on whether or not the higher octane fuel can/has affected the overall health of the car. My best wishes to anyone and everyone who has found an unexpected mixture of frustration and admiration for a vehicle. Thanks much!

Congrats on sticking with your Pac! Currently have 312,000 on my Pac, but have never experienced the level of engine surges that you described. The most I have had to deal with was the butterfly valve on the intake "sticking" (clean periodically with carburetor cleaner) and the transmission hunting for the right gear when traveling 20-25 mph (workaround it by simply throwing Pac into manual gear select when it starts that stupidness).
Regarding how to keep your Pac going, I have considered buying up one or more junk Pacs for donor parts, but the wife would kill me.
Regarding fuel, my Pac has been fed nothing but 87 octane from the discount gas stations since day one. (but I do drive slowly, with 87 it will ping if driving feisty).

You report of exemplary maint. that most would never dream of doing. BUT have you EVER taken the trans pan down(easy to do) and replaced the transmission filter and oil?? If you do that you will see just how much of the trans. clutch pack material has worn away, as it will be laying in the bottom of the pan. The filter is the pickup point for the trans oil to go thru the trans to operate it, if the filter is original to mileage, it's probably plugging up by now! Most all chy/dodge products need this service done around every 60k miles to keep the trans working right. I know, I bought a used 04 T&C with high mileage and shortly after steady running it, it would act like it was going into nuetral with revs to the max. Let it coast a bit from speed and it would act normal again. Changed the trans oil and filter and all has been fine since. Happened around 172K miles and now at 183K miles.