I Just bought a 1993 GMC P 3500 step van. What should I know about general maintenance and upkeep. I have never owned a Vehicle with a diesel engine
before. I had Intermittent problems with power bringing it home over a 500 mile stretch. Some times it would barely do 45 MPH up a slight incline and
other times it would go 60 up a steeper hill. What is causing that? The guy that I bought it from, said that it had 105 horse power and that it got
17MPG. The Engine is a B3.9L/4BT engine with a 4 speed plus low and rear manual and an inter-cooled turbo on it.Engine Data Tag says it was made in 93'
and I think the numbers on the tag are 921918 Is it possible to give it more HP or Torque and/or fuel mileage? Also, how often should the air/fuel and
oil filters and oil be changed. Is there anything else that should be tuned up. Any help or suggestions would be welcome. Thanks