mc1 200tqa oil pressure problem?

[Robert Beatty]

Just finished putting a motor in my 89 200tqa and i am getting a low oil
pressure warning at over 3000 rpm.  While over 3k rpm, I have about 3bar on
the dash gauge, i dont remember what it should be at higher rpms though.  I
have switched the sensor out with another one I had, and same problem.  I
have another 5ktq that i can borrow the sensor from, but that wont be till
this weekend.  In the meantime, I'm trying to troubleshoot what it could be.

I know common reasons for low oil pressure are bad oil pump and worn main
bearings, but these problems are almost unheard of in an I5 from what I
know.  Any other suggestions or ideas what might be the cause?

Thanks
Rob