I am once again dealing with multiple check lights and restricted performance only to have the car run for a week or two with absolutely no issue once I restart. The ABS and Stability control faults are announced on the dashboard and car drives at about 5 MPH with Restricted Performance illuminated as well. What is most troubling is I can restart and their is no light warning light of any kind remaining. I have been in several location where I barley was able to pull off the road.
I have read that this can be the throttle body, low voltage (new battery and was checked with alternator - both fine) or some mystery circuit board in the engine compartment that has bad solder joints. I have also read the codes and they seem random at best - any advice?? BTW 2002XKR

 

Check battery very thoroughly under load as it's by far #1 suspect.

 

Are these problems occurring when you start the car, or while driving? If at startup, start with a battery maintenance if you have a conventional battery. Basically, make sure all the cells have the proper fill level. Top off with distilled water if need be. This can get you a fraction of a Volt at rest.

If this is occurring while driving, it probably has to do with bad connections. Check the battery cables themselves (are they hot?), check the power block in the trunk, check the battery posts at all the fuse blocks. Would not hurt to check the ground cables too. Check for corrosion, or any loose screws.

Separately, get a cheap ELM327, and connect a phone app to it for every trip. Go into the software and RECORD the battery voltage. When the problem occurs, hopefully the recording function will capture something. Or not if the ELM is shut off. Either way, there will be a hint.

The early ABS modules had issues with bad solder joints (basically the power posts), which seems pretty straightforward/inexpensive to fix.

Even if the codes are random, try and build a before/after picture. After the incidents, are all the codes automatically lost? Could again point towards a battery power issue.

 

I think you may be onto something, as I had similar issues when my last battery died, the current battery is a year old and was just tested. Although I did not go through all the connections, might also want to clean the throttle body plugs as well. I also upgraded to a gel battery which has no problem starting the car - so I think it may be faulty connections.