Stalling problem and fault codes

[James]

My truck has been cutting out and stalling at various speeds. Once the truck comes to a stop after spuddering and backfiring, it starts right up. The check engine light comes on a throws a code for the IAC/stepper motor and coolant thermistor. I have replaced both parts and they appear to be working fine. What else could be causing this problem? I have also replaced cap, wires, checked for cracked vacuum hoses, checked base idle and timing, and replaced coil pack. 95 D1 with 4.6

[Mike Hippert]

CHeck to make sure the wires and connectors to the stepper motor and coolant thermistor are all still good?

[rover4x4]

more than likely your stepper, this has been beat into the ground at the www.discoweb.org you may consider searching thier BB as of 3:59pm est the d-web is working

[evilfij]

I assume the intake area around the stepper was cleaned when it was replaced?

TPS, MAF, Fuel pump, bad O2 sensor would be my guesses.

First thing I would do is disconnect the MAF sensor and see if the issue goes away. Then check the TPS with a meter to make sure it cycles through smoothly. There are the most likely culprits if your only issue is stalling at idle.

Stalling at idle is a tough one as it could be so many things. Does it do it when hot? Cold? All the time? Is it random?

The fact that it has a 4.6 should be of little relavance assuming it was done properly (I assume it was chipped and retained the 14CUX style ECU).

Ron

[James]

9 out of 10 times it does NOT stall at idle. I have checked/replaced/cleaned most of what you guys have suggested. Fuel pump and O2 sensors are my next guesses. Other than the new engine and t-case, the truck has 200k on it. As far as I know, the O2 sensors have never been replaced, nor the fuel pump. Could the VSS or ignition amplifier have anything to do with the stalling?

Thanks for all the help.

[BarryO]

Check fuel pressure before bothering with the pump. Also replace fuel filter and the regulator before the the pump, they're alot easier to replace and alot cheaper.