So far still going back an forth with Honda techline. They wanted more data recordings sent in. I'm thinking it's in the splices inside the TPS/MAP sensor. Something with the extra voltage from charging system is enough amperage to cause MAP reading to jump around.
Have you tried whole full new wiring harness for the rig? I know it sucks to do but….
Had similar issues with a customers standby Gen that would intermittently run rough loose a cylinder after a brief warm up and shut down on auxiliary alarm. Went through all the motions, simple things first to cross off the long list then I got into the magnetos, valves ect. All checked out percectly. all was left was a wiring compromiseation issue of some sort or internal diode, bad internal wire giving wrong dirty power voltage to the computer control as the unit ran causing the rough run on one cylinder after warm up then out of the blue the control sees the slight drop out of range and then the auxiliary shut down. With all the other boxes checked (work smarter not harder) that was the only possible cause that anyone in there right mind was not going to take apart and trace each wire or the naked eye could even see even on a meeter.
Took 6hrs labor under warranty, but I removed the original OEM mouse nest of wiring harness cutting my arms in the proses , installed the new one and holy $hit it never skipped a beat. Prior we where getting a call weekly for shut down 2 months on weekly test. Now its been 4-1/2 months with no alarms and 3, 4hr outages with no issues. Needless to say, the invisible wire voltage issue was the problem.
Not saying its yours cuz its a ghost issue. But your fishing right now and looks like you've checked all the boxes but one.
