rough idle/almost stalling

[K3500]

heyyy guys so i had posted a while back i had this rough idle going when i came to stop....i couldnt figure out what it was. neither could anyone els here point to one specific thing. soo i looked online and heard something with the torque converter could be the issue. since when i put it in neutral it idles perfect but when i go to reverse or drive thats when it gets a sputter in the idle like rpms drop from 800-900 down to 200-400....i also cleaned my throttle body witch was very dirty but it didnt help the idle at all..


is this really the torque converter>?
or transmission or??

 

[JollyGreen]

I wouldn't think it's the torque converter. It sounds to me when the truck is under load it sputters.

 

[K3500]

exactly....soo maybe transmission?? engine runs perfect at neutral and park. its drive and reverse that makes it sputter.

 

[Horns]

Check to make sure you don't have a vacuum leak.

 

[K3500]

how can i check a vacuum leak??

i was told today maybe since its under a load when it happens it is starving for fuel. maybe my fuel system needs to be cleaned?? i went to the store and bought a bottom of fuel system cleaner and a new fuel filter. i looked at the old on and i dont think it was changed ever.

does this sound like a possibility to you guys.... i think its weird i have no lights on the dash i would think i could get a code or something

 

[Horns]

To check for a vacuum leak take a spray bottle with some water in it and start spraying it around the engine a little bit listening to see if the idle pitch changes at all.

It might be something like the Idle Air Control. But I guess first I should ask what year your truck is?

 

[K3500]

It is a 2000 5.7l ....

 

[Horns]

Yep, then vacuum leak is all I've got for you. I don't have very much experience with the vortec engines. Maybe someone else who does can chime in.

 

[K3500]

UPDATE: WELL I THINK I MAY HAVE IT FIXED!!!

today i installed a new fuel filter. i have driven around 20 miles, at first it sputtered just a little bit and now it has idled any different at all!! it has a nice smooth idle in park nuetral reverse and drive! i guess maybe the fuel filter was just clogged or something......



the previous owner told me he did a full fluid change and tune up. after i did my oil change the other day it was black nasty oil and a filter that had maybe 20k miles on it!! soo im starting to think maybe he didnt do any of the tune up or fluid changes he swore up and down he did. haahaha looks like ill be doing a full tune up soon