Recently, my C5 had some water damage to the interior and has since had a good amount of electrical issues. The BCM has been replaced and flashed, and it seems that all of the other modules in and near the passenger footwell are fine. I have had continuous problems with the car going into REP(Reduced Engine Power) and is sometimes throwing P1515 and P1516, but other times is not throwing codes at all. I have checked all grounds, there was minor corrosion on a few but they seem to be fine and cleaning them didn't have any effect. The battery is holding charge fine and is fairly new, doesn't seem to be leaking either. I have replaced the throttle position sensor, but P1515 and P1516 are still occurring. As well, all connections around and near the TB seem to be fine, no amount of messing with while running seem to cause the car to go into limp mode. When the code is cleared or if the car is shut off and restart, the car runs fine again. Traction system and ABS go out with REP as well.

As well, my key fob is randomly losing connection to the car, and I have to unlock with the key occasionally. The battery has been replaced but it seems that the issue is with the car and not with the key fob.

I am at a point where I'm not quite sure where I should be looking to find an issue. The TAC Module connectors were in great shape despite being 20+ years old, but I am still considering replacing that next as there is no clear smoking gun. I have also considered checking the pedal to make sure there are no electronic issues there, but I'm not sure how to go about that one. I've listed all DIC codes that come with REP below, and would appreciate any ideas/help that y'all can think of. Let me know if there is anymore information I can provide.

P1626 : Theft Deterrent Fuel Enable Signal Lost
U1301 : High Voltage on the Class 2 Serial Data Circuit
U1255 : Lost Communication with XXX
U1016 : Normal Software Function, History Status Upon Ignition Cycling
U1096 : Normal Software Function, History Status Upon Ignition Cycling
U1160 : Loss of Communications with Left Door Control Module, Lost Communication with XXX Instrument Panel Cluster
U1088 : Loss of Communications with Sensing and Diagnostic Module, Lost of Communication with XXX Instrument Panel Cluster
U1040 : ?
U1176 : Loss of Communications with Remote Function Actuation, Lost Communication with XXX Instrument Panel Cluster
U1064 : Normal Software Function, History Status Upon Ignition Cycling
B0333 : Outside Air Temp Sensor Open
B2282 : 12V Power Feed #1 Fault
B2286 : +5V Reference Fault
B2284 : 12V Power Feed #2 Fault
B2262 : Mirror Horizontal Position Sensor Fault
B2264 : Mirror Vertical Position Sensor Fault
B2283 : 12V Power Feed #1 Fault
B2287 : +5V Reference Fault
B2285 : 12V Power Feed #2 Fault
B0851 : Battery 1 Out of Range
U1300 : Low Voltage on the Class 2 Serial Data Unit