I am running into problems when Plum Broke starts getting up around 210+. While idling in traffic or parked my oil pressure will drop to 0psi on the gauge. I have checked and double checked the oil level and it is full. This only happened one time on me last year while pulling two four wheelers behind it in 95* F weather w/AC on. Well it happened to me a lot today and I didn't have the AC on. As soon as I idle it up it is fine again or if I am traveling down the highway at 55mph +. Only happens in hot weather while doing a lot of stop and go driving. It has fresh coolant as of last year and it never runs hotter than 215-220. ~180* highway driving and ~210* stop and go driving.

1996 5.2 Limited: 180* T-stat, Performance Distributors Ignition Upgrade (10mm live wires, screamin demon coil, brass terminal cap and rotor), Autolite 3924s, CAI, SCT Tuned, IAT Sensor relocation.

What could be causing this?

 

The thermostat my get stuck, the radiator could be clogged, bad water pump. About the oil pressure, I will attach manual gauge and see if your oil pressure if good. If your oil pressure drop on manual gauge then you have bad oil pump or main bearings are gone, but you should heard that (loud knocking). Check oil sender unit for leaks ( by oil filter) and replace if needed.
To diagnose coolant flow, take the cap off (while warm but not hot) and see if coolant is moving in radiator. Coolant should start flow at 180. Before taking the cap off, squeeze the radiator hose. If is hard then do not take the cap off or you will get burn.

 

Could be a bad oil pressure sending unit. Maybe it won't pickup slightly lower than normal oil pressure. I had an s10 p'up that when idling the oil light would come on. Checked the oil pressure with a man. gauge and oil pressure was within okay range, changed sender and problem fixed.

 

I believe it is just a bad sender unit. Looked it over today and am going to tackle changing it next week.