Thank you for the reply Neukam

There are some morsels in there I was hoping for that I can check out no problem. Very helpful. Glad to hear there is some timing built into the module. It was boggling my mind. Now I don't feel so bad. I thought about hooking up TP but I was frustrated and needed a break at the time. I am guessing if the brown wire is unplugged, the timing changes seen using the light at the balancer would not show up/match there anyway which would have been frustrating again. I decided to swallow my pride and reach out. Glad I did.

The engine is in the truck currently.
The TBI is native to the truck 93 GMC 5.7. Other than the serpentine pulleys, brackets and AC everything else has been replaced.

No check engine lights or logged codes currently. Initially I had the wrong knock sensor but once I procured and installed the correct unit, no codes other than the occasional CD42 from disconnecting the brown wire. This is the primary reason for thinking it is/could be mechanical in nature. No codes + engine funk usually means mechanical but my gut is saying it may be the tune since everything in the engine has been changed beyond what the computer is tuned for at the factory. Backfire at the exhaust could still be lean/timing related too. Just wasn't sure where to begin. I will check out the Main Spark Table vs MAP vs RPM tables and AE vs MAP / AE vs TPS. Hopefully it will net some improvement I can build on.

Now that I have had some time to contemplate, I don't know the HV oil pump is causing an issue. I ran the engine with the carb/HEI setup on the engine stand for 10+ hours over a few days and never had an issue even @ 3/4 turn. I'm thinking I may replace it anyway. I threw it in there on a whim and it hasn't set right with me since then. Just hate to mess with the seal etc. Dry as a bone currently but it is a reusable so I may just suck it up and make it happen later. Sooner if I can't make headway pretty quick. Clearances are pretty tight for sure.

I will upload a current log and the modified log once I get back out there to tinker again. The only log I have is pretty jacked up due to the CD43 I had because of the wrong knock sensor. The computer was intermittently adding 4 degrees of retard messing with any stable readings I thought I was seeing.

Thank you again for the advice. I will let you know how it goes.

Can anyone explain what Limp home symptoms are? I know it runs like crap but there must be some standard signs to look for. Possibly? Perhaps a quick-check like programming idle RPM? ....I just answered my own question didn't I?