[abaird]

I think your next step would be to unscrew the oil pressure sender and plug in an oil pressure gauge. Then go drive around and watch the gauge to see if it does the same as what the gauge on your instrument cluster does. If the gauge reads normal then it could be a bad sender or a bad cluster. I know some of the newer chevy's have problems with the clusters doing weird things but I don't know about 99's. The crappy service literature I have at home shows the sender on top of the engine but I can't tell if it is the front or rear of engine. I'll look on alldata tomorrow to find an exact location.

As for the oil line leaking, I wouldn't suspect high pressure to be the cause. I have replaced a lot of oil cooler lines just because they are junk and leak becuase they wear out.