This may indicate you need to put a higher weight of oil in the engine. Or the oil in the engine is old and has thinned.
jeeps don't actually hold much pressure under idle when they are warm if your check gauge light isn't coming on then you have no worries
The oil pump is driven by the engine. Turning the engine faster means that the oil pump spins faster, this creates more oil pressure. 80 psi is normal at high rpms, and will not cause any problems.
Normal idle oil pressure would be around 30 psi. Minimum pressure should be about 10 psi.
This would be a 9004 series halogen bulb available almost anywhere.
your oil pump is bad
Should be at least 10 at idle. 25 at idle would be better.
That is almost always an indication of a failed transmission. Check the fluid for a burnt smell.
A Cherokee would have the AW4. A Grand Cherokee would have a 44RE.
your catalytic converter is probably stopped up
AC pressure transducer.
Low oil level, failed oil pressure sending unit, plugged oil filter, internal engine problem.
might be a bad head gasket or radiator might be clogged or timing might be off you would need a machanic to look at it and diagnose it
That is certainly not a Cherokee word, since Cherokee has no "ch" sound. It would be totally meaningless to a Cherokee.