Funny oil pressure at Trans Sport 3.8

Hello guys, hope I’m right here with my concern: as already mentioned, with my oil pressure or at least with the oil pressure indicator something is not in order. The car drives, as I mean as an unprofessional, perfectly, but during idle the oil pressure indicator stands in the red area. As soon as gas is given, it commutes between the bottom and the middle until it lands again in the basement at the next stop. Equally strange: the cooling water temperature indicator hardly reaches the first marking (from below!), no matter how far or long I drive. Did you notice similar to your car? Engine oil level is just above middle marking, color is nice brown, but last oil change is unknown. Cooling water is also correct. Machine has now almost 120tkm at year of construction 1992, so for a large V6 really entered, I think. I am grateful for every tip!! Thank you, bayernpfalz