Just a thought ....

Had a similar problem with my Turbo Grand Prix's oil pressure gauge when I bought it, even replaced the sending unit (twice), but it still would go berzerk. I checked the terminals in the connector that plugs into the sending unit, and found that they had spread some, which would intermittently break contact with the pins in the sending unit and send the gauge haywire. I pinched them back to where they would be tight on the sending unit's pins, and haven't had a problem with it since. Just something to check...

Brian J