Code PO58B

Hey SQM,

Thank you for reply, the service bulletin was exactly what I needed to point me right direction. It's a friends car that's having these issues, when he told me what it was doing and before reading MIL codes was thinking vacuum leak.
Limited knowledge of engines that don't have them archaic parts like carburetors, distributor caps and you could literally climb into engine compartment by removing a part or two et: radiator etc. Hahaha
Knowing when to ask someone that has the knowledge you don't is the best knowledge to have.
Will follow the steps of bulletin if both main and aux. Batteries test good.
Checked out link in your reply, no problem with testing for faulty connections, wiring etc.
My work consisted of troubleshooting, resolving issues of large extrusion, injection machines, 20+ yes.
To recently troubleshooting, repairing restoration equipment, so very familiar of process just a different animal.
Car owner lives over the bridge in Philly I'm in Jersey, shooting for one day this week for him to bring car over.
Will definitely let you know how it goes or if I get stuck on something have no problem asking questions.
Thanks again SQM, your knowledge and response surely saved me a lot of time of searching and probably going in circles in the search process.
Be safe and I will post follow up of what caused the issues and what resolved them.

Hey SQM, man I just spent over 20 minutes typing not my forte at all) moved my phone so keyboard was positioned better inadvertently pushed a side button or something wiping out what I had typed so far. Hahaha.
Starting over, going to condense this but was going to follow up with pictures in another reply anyway.
Took quick look at car last night, it was dark and my buddy was pressed for time, will get a pic and want to look under hood again to be accurate on what most likely caused problem and include in follow up.
Found that one of the connections/wire to post/stud in the what I now know is the fuse battery distribution block was so lose it could be moved up and down between nut & plate. I went in house to get driver with insulated grips, wasn't sure if the wire was hot.
As you know DC packs a wallop, tool
touches something that completes circuit while tightening connector, hand holding tool is now part of the circuit.
When I got back outside he had it tightened and had to get rolling.
I'm not positive of which one was lose, if he isn't sure either. I'll know by looking at block again. I don't think it was #4, I did some searching online earlier get informed on how that block is configured.
If I understood it and source of info was correct #4 is aux battery. #3 power steering module 1 and 2 interior fuse block. #4 is independent of #s 1, 2 and 3 which are connected by a plate which allows power to be distributed across the three. Is that accurate?
I didn't have time to clear the code but it cleared itself rather quickly, I assume after a certain amount of cycles.
It appears that lose connection was the problem. I will check with him to see if the rough idle has improved.
Will definitely send reply with accurate details asap.
Sorry for such a long ass text.
I have to laugh when texting with friends, family etc. On phone, 20+ minutes typing what would take 3 minutes to say by using phone as it was intended to be used. I'm pretty certain theses things have a feature that can be used to make a call.
Be in touch soon, also I have told 3-4 people this is the site to use if stuck on car repair. Your thoroughness with answer ie: attached docs, link to step by step instructions to get to problem is impressive and greatly appreciated.
Thanks man. Will post again when I have better details. I could be mistaken on #4 not the one that was lose, was rushing and didn't have chance to look closely and take pic. Will have that info in next reply.