Ford Repair: oil pressure 92 tbird 3.8, oil sending unit, odd note

Question
92 3.8l sat for 3 years. was daily driver.  put motor in 95 t-bird.  oil pressure did funny on startup. It pegged. no oil on the ground though, was all nes fluids and filters of course.  After several restarts pressure dropped, then fluttered, on revving started working normally.  continues for 60 +/- miles.  then when coming to stop pressure flutters then drops off. On restart works fine after heavy accel when pedal is let up pressure repeats pattern.  I suspect sticking spool of pressure regulator, in timing cover housing because of setting up, what do you think. Odd note after 60 +/- miles the problem seems exacerbated by heat?  This leads me toward bearings, cam, mains or maybe pump but why the perfect performance until the mileage I spoke of. mileage on motor...120,000=/-  Thanks Troy

Answer
first of all which oil sending unit did you use and if you used the the one that came with the replacement engine was it correct like were they both for guages or lights there is a difference and that would explain the erratic reading.

yes it could be a sticking problem but run an oil pressure test to verify proper operation of sending unit and guage plus this will let you know if pressure is really dropping off then yes very well could be bearings-another thought is sludge in the bottom of oil pan sucking up to screen the more you drive after shutting car off will settle back to pan until next time.