First off it's good to be back, not sure what happened to my old account but I owned an 87 Cherokee and was here for 5-6 years and ended up selling it and I just recently bought a 2001 Cherokee classic with only 130,000. Now on to my question, I have good oil pressure under acceleration but as soon as I come to a stop and idle the oil pressure drops to 0 and the check gauges light comes on. I was told that the elbow at the oil sending unit needs cleaned or its possibly a bad sending unit. Should I pull it off and try to clean it with a pipe cleaner or run seafoam and changed the oil again as I am thinking it is possibly sludge causing the issue. Sorry for the long post I'm just excited to be back.

Verify the oil pressure using a mechanical test gauge.

I would check with a mechanical pressure gauge to start. It could be a bad sensor or a clogged port like you mentioned, replace sensor if mechanical gauge checks out if pressure is with in spec (13 psi hot idle 40+ psi cruising). Seeing that you have a 2001, I would also look at the head to see if it was replaced. You have 0331 head on that which is prone to cracking. If head is cracked there could be coolant mixing with the oil causing low oil pressure.