Your fans going to wide open plus computer codes make me suspect the grounds for the computers (one for both). Mine was a good 8 months out of the shop before it went koo koo and I found it had no nut on the ground post whatsoever. If yours is just not tight or slightly corroded it could match these symptoms. It's a royal pain to access unfortunately because the wiper arms have to come off to access them. But if the easy things aren't solving the problem then check it out.