i have a 1998 12v automatic and it stalls out when you come to a stop or go to back up stays running in neutral or when transmission is still cold

Torque converter?????

what's the idle speed?any moAny mods done to the truck?

idle speed is 600-650 when in park or neutral. the stall happens after its warmed up and when im coming to a stop or a put in reverse and dies down to about 400-550 then it just shuts down, if i hold my foot on the brake a little and and push the throttle down it will stay running. one of my friends thought it might be the torc converter but seem to shift fine going down the road and if it is will it hurt the truck if i keep using it, and there is no mods done on the truck it is 100% stock and has 88k on it original motor trany

sounds like POSSIBLY the governor springs may need some attention. I know when you replace the governor springs (with something rated higher, like 3k or 4k), and you don't get the spring tensions set properly, it will do the same exact thing. There's also an idle screw that may have backed out a tad. I'll see if I can find the info for you. 450 is way too low, and 600-650 is also too low. Needs around 750 (manual) or 800-850 (automatic). edit-- here's a decent 'how-to'.. with video. http://www.dieselbombers.com/12-valve-2nd-gen-dodge-cummins-94-98/86605-how-adjusting-idle-speed-12-valve-p7100.html

thanks for the info. i might take me a couple days but i'll get back to you and let you know how it turned out

The first thing that I would do is bump the idle up to where it is supposed to be. It is supposed to idle at 750 RPM in gear with the A/C on. If you have not installed a GSK (governor spring kit) I highly doubt that they are your problem. It sounds to me like the idle is just too low.

I doubt it, too, Tom, but I know I experienced the exact same issues after doing the 3K GSK on my ppumper. I also had to bump the idle on it.vtdodge, any updates?