My Tahoe is an ex cop car so it’s a wiring nightmare. I also don’t know much of anything about wiring.

A few days ago we had torrential rain and some flash flooding. I let my excitement get the best of me and bombed through some of the larger “puddles.” I’m now getting codes for TCM, FCM and communication bus off. At first- when accelerating from a stop to about 1500 rpms it would completely drop rpms and throttle response then jolt forward and recover back up to 1500 and accelerate as normal. Now it is just completely stalling at that 1500ish rpm point however I’m able to put in park and fire back up. Check engine light goes on and off although it should remain on regardless because I have a small EVAP leak and I haven’t cleared the codes in months.

Not sure if this is relevant but when I got home and plugged in my scanner the FCM data was reading 4.0V and a crazy astronomical desired pressure. I backed out of the screen waited a few seconds and it’s now reading 9.87V and normal desired pressure.

Any help would be GREATLY appreciated. I’ve been thru hell with this car since the day I finished paying for it (2 new engines, mechanic ran a stop sign on a “test drive” and totaled a sedan. another mechanic stole my PA system and grille fire/ems lights, had an electrical fire from plugging in trailer lights... I’ll stop there)