Unsteady oil pressure...fills with oil often...oil pressure so low car will stall and lock while driving...shops can find nothing....need help fast

Are you saying it is burning oil and you keep having to add oil? If so, it is apparent the engine my need an overhaul. The oil pump needs replacing also. Could be the engine was neglected by the previous owner and the oil was not changed at regular intervals. This can cause the oil passages to clog and also cause worn main & rod bearings along with crankshaft journals. The oil pump does not create pressure it only creates flow and the pressure is created by resistance of the oil flowing through orifices and by the amount of clearance between rod bearings and journals. If it is not burning allot of oil try this. Purchase a can of Seafoam engine treatment at almost any auto parts store. Change your oil & filter. Use the correct weight oil and a good filter such as Purolator or Wix. Add one can to the oil as instructed on the can. Follow the directions on the can and repeat the procedure 3 times making sure you Change the oil & filter each time. This may clean out the engine oil passages if this is the problem. If this does not help and changing to a quality filter does not help, you may need an engine overhaul. Of course the oil pump screen can also be clogged or the pump can be worn. The Seafoam may clear the oil pump screen. It is worth trying before you go to the expense of an overhaul.