89 4.3 4x4 - Oil Pressure high - pegs gauge
 

Got the oil changed and not two weeks or so later the oil pressure gauge started pegging out. When it is first started it goes up a little above half way. If you push the accelerator pedal it jumps up and pegs out. Sometimes it runs rough (hesitates - jumpy), while sometimes it seems to run fine. When at idle the gauge goes back down.

Any ideas? Going to change oil again and get a new filter first and see if the situation changes.

Check to make sure that the PCV port on the TBI is not plugged. I had high oil pressure that would blow oil out the dipstick if it was not seated all the way. It would blow out the PVC valve. I did not get to the root cause until I decided to rebuild the TBI unit and the port for the PCV valve was totally plugged up with carbon deposts. There was no crankcase ventilation due to the clogged port and the crankcase had no way to vent. Once I cleaned the TBI unit and put it back on the car my oil pressure returned to normal.