Workhorse "Reduced Engine Power"

Thanks for all the replies. I finally got a chance to take it to an authorized Workhorse repair facility in Penticton, BC and they had it for awhile testing this and that. They didn't seem too knowledgeable about this type of problem but they had a vast network to draw on. The service manager talked to mechanics that he knew that had lots of experience both at GM and Workhorse as far away as Chicago. He finally found a solution with advice from the local race track speedway manager. Told him the symptoms and he immediately suggested the TPS sensor on the transmission. That was removed and cleaned and reattached and the problem went away almost completely. I got home from the trip and went to dump the waste tanks. Put it in reverse and hit the gas and then brake several times to agitate the black water tank and it went into reduced power again. But generally I'm satisfied with the service received by Cullen Diesel in Penticton. And I advised the dealership where I bought the motor home of the situation and they picked up the bill.