What type and weight of oil are you using? You are getting a little on the low side as far as pressure. Are you using any oil? A thicker oil might help with the oil pressure and going to synthetic can help as well. You could also install a high volume oil pump. I expect the bearings are getting a little worn or your pump is worn out. Bearings being a little loose won't hurt anything accept oil pressure. If you have knocking, then they might be a little loose. You can check the bearing clearance with Plasti-Gauge when you install a new oil pump. I recommend you using Mobil 1 15W-50.