I'll try to keep this short...have an '88 D100, 318. I started having shutdown problems 4 months ago. Each time I let my foot off of the accelerator, she would stall. Replaced torque converter, replaced a malfunctioned fuel injestor, and just installed a new fuel pump. Now she idles great but still...when I drive her, she stalls when I pull off of the accelaerator and begin to brake. She will even try to stall when she is in park and I rev up the engine and release the accelerator...it wants to choke out.

The O2 sensor is about a year old and I am at my whitts end...any words of wisedom out there?

Thanks

 

Check the idle air controller and the wires that are connected to it. Mine had the same problems and it was such a hassle to drive.

 

Sounds like the EGR might be sticking open. Does the ambient temperature or the temperature of the engine have any effect on when this happens or is it all the time?

PS: Bear with my responses being edited instead of one piece because of my internet connection being so erratic.

 

On the older TBI throttle bodies there's what I always referred to as a 'dash pod' that the linkage rests on. Looks somewhat like a bolt with a couple of wires running to it IIRC. It's there to allow the throttle to slowly close instead of slamming closed when you take your foot off the gas. This may be bad and allowing the engine to stall out. Just a suggestion.

EDIT: I did a lookup on the part and it's called the Idle Speed Control Motor. NAPA part # MPF 32191. Cost is in the $75 range but may be purchased a little cheaper at another parts store.

 

The ISC motor has 2 functions. The cushioning job and the base idle setting. The computer controls both of these functions using the ISC motor. Usually when this actuator fails (which is very rare) the engine base idle also drops unless someone has messed with the adjustment on it. You can test this by disconnecting the electrical connector and then turn on the A/C or some other engine load.

 

Many thanks folks. Sounds like I'm off to install an ISC. Keep your fingers crossed!

Appreciate the help

 

Mine does that too, and my idle speed motor doesn't work either, I just live with it for now. I can rev in neutral with no problems, but if I stab the throttle quickly in gear (not that I would or should) but it'll stall it nearly every time. Eventually I'll have something with a 4 barrel attached to it under the hood.

 

In the meantime, you can screw out that bolt on the IAC/ISC to the point where it will idle cold and not stall. When mine was bad, I set it to idle at a shakey 700 cold and 1700 warm. You might get some strange looks, but it will get the job done for a few weeks.

 

Wow, mine isn't quite that extreme. Cold, it idles around 550, but that's only for about 5 minutes. Without a/c, in park or neutral it runs 750, 700 with air, and around 650 in gear. Any faster and it feels like it's beating itself up going into gear. Any lower and the a/c compressor doesn't always want to kick in.

 

I had to back my screw all the way out but it wasn't enough so I backed it all the way in and glued a 5/16 mini socket to it haha ghetto rigged but its still working