i bought an immaculate 99 durango off my wife's parents for my wife to haul the kids. One owner, well maintained, but its a used truck and has issues. it is and automatic with the 5.9 v8
issue #1: it bucks/stumbles for about 5 seconds when it is started and warmish/cool, it does have a CEL on too and it will get checked soon (just took possesion of the truck yesterday)

issue #2:if your give it some gas to accelerate briskly it doesnt want to shift, it will redline and still not shift, and when you back off the gas it reluctantly shifts.

issue #3: i come off the highway after driving for a bit and stop at a light, then when i go it starts in 2nd. i pull away with it at 1500 rpm and not pulling hard at all, then it down****s and pulls, then shifts to 2nd. its strange

issue #4: #8 sparkplug fouls up between changes, i have heard it can be a plugged cat doing this, is that true?
it seems to not have enough power for such a big motor. my ram has 700k km on it and pulls better through town

the trans needs a fluid and filter change i know this, but these are some strange things to be going on, and am wondering if there is some other things i should do while i have it open.

thanks in advance for any advice, cheers

 

1) low speed idle issues are cause by one of a few things, bad IAC, bad TPS, or bad battery, not knowing how old the battery is that would be my first guess for you on that

2) check the output speed sensor on the transmission, its on the driverside of the output shaft

3) not sure, but the speed sensor mentioned above controls shift points so start there.

4) check the plenum gasket on the truck (open the throttle body and shine flashlight down, it should be relatively clean, not soaked in oil) a bad cat will NOT cause fouled spark plugs

 

My calls would be:

+1 on #1... bad battery.

#2... pressure governor solenoid

#3... pressure governor solenoid

+1 on #4... check plenum

 

i am sorry i didnt write right on the first problem. it stumbles while driving for about 5-10 seconds after it is running for about 2 or 3 min when warmish cool.
i called my tranny guy today (things like this eat at me, and my wife must drive a perfect truck) he is knowledgable and built me a killer th350 for my 2wd blazer this summer for a real good price. he said the same as you guys, the speed sensor, but he also added it would be smart to tighten the bands on it all while doing a fluid flush and filter. so i am going to take it to him on friday.
on the plenum gasket, if there was a plenum leak wouldnt more than 1 cyl gum up? it isnt oil deposits, it's cabon deposits and its only between plug cahanges. i have had a bad plenum gasket on a chevy one time when i tried to rush a head job, and 2 cyl fouled every 3000km. (i have the old one, the owner kept it to show me). the way it was explained to me is when the cat plugs it does this because it is the last cyl before the Y pipe. and if left like this it will crack the heads. this thing was babied in the city so im sure there has to be some sort of gumming up.
i muchly appreciate the responses

 

found it
https://dodgeforum.com/forum/2nd-gen...um-thread.html

half way down the page, i thought i saw it on this site

 

When my plenum gasket blew it only fouled #8.


Posted from Dodgeforum.com App for Android

 

the oil you are sucking in from the bad plenum is what fouls the #8 plug, not a bad cat, burning oil for too long can clog the cat too, so there is some link, but not in the direction you are putting it together(that guy has the causation backwards)

also NEVER EVER FLUSH A TRANSMISSION, change the fluid and filter only (a purge of the fluid is acceptable, however if you keep up w/ the fluid changes it will not be necessary)

 

thats what i meant, a drain and filter. and i will check out the intake as well.
is there any porting work that i can do to the intake if i have the plenum apart? it looks pretty set in its design. i was thinking about a few things it may benifit from, and yes i have done this before but with carbureted intakes, and they are fairly strait forward

 

also any cheap performance mods outside of the normal exhaust, air intake and pcm would me much appreaciated

 

I had those problems with my d and what i did to solve those issues were.

1. Replaced the coil, wires, rotor, cap and plugs.
2. Replaced the governor pressure solenoid and switch, fluid filter change.
3. New battery,
4. New idle air control valve, tps sensor, map sensor and out put speed sensor.

I replaced the igniton system due to fouled up plugs and and eventuialy a failure to start.
The tranny had issues, slipping and it seemed like it wanted to start in 2nd gear.
The random idle, up down. and rough start problems i fixed with replacing the sensors and the iac.

My sugguestion to you is to do exaclty what i did.

The ignition replacement will cost roughly $100.

The sensors will cost about the same.

The tranny fix is going to run you about $200 and up depending on which fluid you choose. Always use atf +4 is these trannys.

What you choose to do is totally up to you!!!

Also cleaning out the diff's and replacing the fluid is always a good idea. You never know if it was ever serviced. Also most mechanics will only cleck fluid level and add if needed when taken in for a tune up.