So my 93 s10 blazer 4x4 is dropping oil pressure at decel and sitting at idle my oil pressure gage bounces from 40 to 0. Any idea what may be wrong

 

Did you check the oil level - Not being a smart aleck. My kid complained of the same thing and I bought a new Oil pressure transmitter and a new connector pigtail. Right before I was gonna cut the old connector I checked the oil and there was zero oil on the stick.

It was literally 3 quarts low it was also like 2,000 miles overdue on an oil change... So basically he drove almost 6,000 miles without checking or changing the oil.

 

The pressure transducer can go out on these. I had it happen 150 miles from home in the middle of nowhere. It was a long drive back home but was glad it was not the pump.