1994 Pontiac Bonneville Adding new coolant every week

Sounds like your car has the high-mileage blues? As far as the coolant, can you find any external leaks? If not, it may be an internal leak, gasket somewhere.

The general specs for oil pressure shows 60@1850 rpms. I've seen other high mileage vehicles where the oil pressure would drop off the map at idle. Maybe the engine needs an overhaul? If I replaced an oil pump, I'd do more than the pump.