94 Grand Am GT oil pressure and gauges questions

[docprego]

I just bought a 94 Grand Am GT V6 with 65K on it. The extensive test drive went great and we thought the car ran fantastically.

On the way home I noticed a few gauge issues. First the tachometer sits at 0 and then kicks in sporadically, no big deal as it is an automatic anyway. But what I am concerned about is that the oil pressure gauge jumps up to maximum, I mean past 80 instantly upon starting the car and stays there.

Because of the obvious tachometer problem I am thinking that the oil pressure gauge is not reading correctly and that this is a problem with the gauge(s) or the information it is receiving, not with the engine. As I said the car runs beautifully. If the oil pressure were truly this high, would the car run this well? Also how could the pressure jump to that level immediately upon starting the car, wouldn't that take some time? My hunch is that it is the gauge but would appreciate any input you may have. Lastly the guy I bought it from told me that the gas gauge had just been fixed, in fact the dashboard was not properly put back together as there is a broken retaining clip as a result of that repair. So I have easy access inside the dash to look around right now.

Thank you,
Mike

[docprego]

Anyone? Advice desperately needed!