Umm, he has TBI, it's a 4-banger.
2.5L I4 TBI (fuel injected) - 121 hp @ 5000 rpm, 135 ftlb @ 3500 rpm - used in '87-'90
It's not uncommon to see the oil pressure rise (my 4.0L pegs the gauge at idle when cold) at a really high idle, although I doubt the accuracy of the gauge due to the afore-mentioned sender unit's reputation. Replace it if you feel the need to, FWIW I haven't replaced mine yet...
As for the high idle on start up, start with checking for the vacuum leaks that bigredcherokee mentioned, and then thoroughly clean your throttle housing & idle control motor.
Originally Posted by bigredcherokee
Rob you could have a bad sending unit or gauge. Do a search on the forum and it will bring up a tone of info. As for you idle I beilieve your carbarated and could have a sticking coke or vacume leak not sure. One delt with a carb on my 90 long time ago and I pulled it off and went MPI.