Have a 03 ram 1500 w/ 4.7L AT and have been having issues with erratic idling. For example sitting at traffic lite the idle will spike up & down 2-300 rpm and may die and may not. Have had motor just die while turning at an intersection. Then was on road heading home for work, had cruise set about 70mph, then outta the blue the speedometer bounced up & down a couple times then stayed at 0. At about same time the ABS & Brake lites came on. I replaced the sensor on rear differential. No change on anything. So replaced by sensors on transmission. Once again no changes. Checked the junction/plug connector on firewall behind battery and found no corrosion/moisture. Checked connectors on ABS module and on PCM as well and found nothing. So decided to go ahead and replace the PCM thinking this had to be it. WRONG THOUGHT. So this is where I'm at and I am at a complete loss for where to go with this next. Any thoughts would be much appreciated.

 

Just had the exact same thing happen to my 02 Ram yesterday. I have checked the sensor connections and did a quick visual of the wires and decided to order the rear diff sensor (knowing darn well the easy thing never works). QUestion for you, how does the ABS connector un-plug? That was my next thing to check but did not want to break the connector and screw myself further. Thanks and keep posting your trials and tribulations.

 

You most likely have a wiring problem, since you replaced the PCM without improvement. Electrical diagnostic require special tools for probing the connectors. The service manual talks some about it but getting someone that had experience doing it would probably be best.