Low Oil Pressure, Oil leak, Check Gauges light on on 1999 Chevrolet Express 1500

My 1999 Express 1500 conversion van has a problem where it has very low oil pressure at idle, when coming to a stop, and any other low rpm status. This does not happen during the first 2 or 3 minutes while the engine is warming up, where the pressure seems higher than normal. I have recently had the oil changed, but the problem started before that. Also, oil leaks at higher than idle rpm, I can't tell if it's coming from oil pan or elsewhere, but it's dripping on the exhaust crossover pipe. Any answers? Thanks.

Asked by for the 1999 Chevrolet Express 1500
You need to have a shop trouble shoot this because if the oil pump is failing it will destroy the engine with low or no oil pressure and its a lot cheaper to change the pump than the whole engine and you never know it might just be a faulty sending unit and you can find a shop here