So I've been slowly fixing up this completely stock v-hicle, other than aftermarket radio, and  try to address every little thing  I can find. To my knowledge, the only issue I have is that

a) the 4WD won't go into 4Lo. It tries, jerks a bit trying to engage, but  then reverts back to 4Hi but I am living with it, as I never use it, but eventually would like to fix it. I do have some extra parts for it including an NP246, but for now it sits as it's not my skill set and also too old to pull it off myself).  

b)  driver side heated seat element is not woking

Also, historically, it did undergo a complete engine rebuild, and I did swap out the main computer at one point, but as it turns out,  I dont think there was anything wrong with the original (which I still have).  Doesnt meant there wasnt, and doesnt mean the current one doesnt have an issue either.  (I suppose I could swap them out again and check codes, maybe someone can comment there)

Every few months, I throw the code reader on it and log that info. I use a Foxwell NT510 Elite scanner using the GM analysis package.

My fuel trims look excellent and I think my MAF  look fine also, at least at idle they seem reasonable. Also,  no check engine light visible.

My codes are as  follows.

PT - P0605, U1042, U1064, U1193

Passlock – C0504, U1016

EVO – C0504, U1016

I am not noticing any issues driving other than about 14 MPG city which is slightly lower than a few years ago, and  other than the 4wd issue and was wondering if someone might have some insight on the above.   I'd love to be able to try my hand at troubleshooting /debugging these