97 tj alternator or pcm?

[faTJeeper]

After getting back from a wheeling trip this weekend jeep not running right. will run till gets warmed up and this it starts stuttering and electrical pretty much dies. giving codes that it is running lean and that there is incorrect voltage. the last trail i was on consisted of a going up a river. i drove 6 hrs home without any problems and then right when i was getting home started having problem. first thought was that the water messed up the alternator. looking in fsm suggests it could also be the pcm or maybe a bad ground for the pcm. i was thinking it's more likely to be the alternator or ground since these things could have maybe been affected by the water while the pcm most likely wouldn't have been. any ideas would be greatly appreciated.

97 tj 2.5l manual